$275.00 – $775.00
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Rod Mod
During the “Rod-Mod” process, we take the LS3/L76 intake manifold and install radius bars lengthwise in the plenum. Through research and development, we have learned that air does not like moving over sharp turns – it creates unwanted turbulence. The radius bars we install are carefully selected, measured, and cut to a specific length and assists in transitioning air from the main plenum into the runners. This helps to maintain proper airflow and velocity. In addition, we minimally grind and smooth the area inside the runners where the injector boss protrudes into the runner, ensuring minimal disturbance to airflow from the injector boss. The Rod-Mod is ideal for forced induction applications, as well as nitrous applications as it does not compromise the structural integrity of the manifold during high-pressure events.
Est Gains: 6 HP for bolt-ons & 12 HP for cammed setups.
Porting Mod (Popular)
During the “Porting-Mod” process, we begin by removing the vertical stands that run inside the manifold plenum. These stands are large and very obstructive to flowing air. Once removed, we adequately seal the plenum floor back up, and slightly grind/smooth the floor of the plenum. Next, we port the air inlet section of the manifold along with grinding/smoothing the injector bosses protruding into the runners. Once all porting/grinding work is completed, we then install the same carefully selected radius bars that we use in the Rod-Mod. Again, these bars greatly assist with transitioning air from the plenum into the runners, maintaining maximum airflow and velocity. The Porting-Mod is ideal for naturally aspirated applications and performs at its best in a cammed setup. At no point do we recommend the Porting-Mod for forced induction or nitrous applications, as the stand removal does lessen the structural strength of the manifold.
Est Gain: We don’t see significantly more peak power over Rod Mod (+1 or 2 HP), but we see it across the entire powerband and the midrange torque increase is worth doing the Porting Mod if you can.
Porting Services
Available to order
Piston Rod Combos
GPI – Track Attack LS3 High Compression Dome Piston and Rods Package (5th Gen Camaro / C6 Corvette)
In Stock
Cylinder Heads
In Stock
Tuning Services
In Stock
In Stock
In Stock
We have often wondered and been asked if porting in addition to the radius rod addition would improve the LS3 intake manifold. We figured it would be a great time to find out – so Mike and Ryan quickly built 2 manifolds, one with just rods and the other with the stands removed and ported. Both we and our customers have tested the radius rods on chassis dynos and at the track many times and usually see from 6 to as much as 12 RWHP. We saw 11HP at 6600.
Both we and our customers have tested the radius rods on chassis dynos and at the track, and usually see from 6 to as much as 12rwhp. We saw 11rwhp at 6600.
The ported version looked quite a bit better. We were disappointed with the positive result as the porting is very labor intensive and it’s probably going to be requested a lot going forward. Although we didn’t find significantly more peak power, but we got it everywhere and the midrange torque increase was worth the effort.
We didn’t find significantly more peak power, but we got it everywhere and the midrange torque increase was worth the effort.
The “Mod My Manifold” option allows you to send in your LS3 / L99 Intake Manifold in to us (shipping instructions below) to have the modifications completed. This option is best for the individual who doesn’t use their car as a daily driver, or can stand for the car to sit for a short period of time – while we are modifying your manifold. This is the least expensive option. Typical turn time is around 2 weeks.
The “Buy Modded Manifold” option is our most popular option – because it doesn’t require any downtime at all. We send you one of our modified manifolds from inventory.
We will optionally buy your stock LS3 manifold back for $350. Just send yours back in the box you received yours in. It’s that easy! When we receive yours (and verify it is not damaged…) you receive your core refund back.
If you decide to ship us your stock manifold back for the $350 credit – pack up and ship your intake manifold to:
Gwatney Performance
1301 T P White Dr
Jacksonville, AR 72076
Please include a copy of your invoice in the box with your manifold.
Please remove all vacuum hoses and sensors from manifold before shipping.
We HIGHLY recommend using generous amounts of shipping peanuts / bubble wrap. We’ve had a few “less than cautious” packing jobs (thrown in a box and taped up) which led to manifolds getting damaged in shipping. Unfortunately we are unable to issue core refunds on broken / damaged manifolds.
Intake Manifold Heat Shields
2 in stock .
Porting Services
Available to order
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The test numbers are on a stock headed LS3, the radius rods smooth out turbulence in the intake manifold. It is not for a support deal. We have seen guys run them on a boosted application with no failure but do not suggest it with the center supports removed. The rods would no be beneficial at that time. We see a lot of our customers sell the ported manifold and go back stock when they add the boost.
You will not be able to make that intake fit properly. It will need to be replaced with a square port manifold. If in a truck, look for one from a 6.2 Denali or Escalade.
You will receive the $350 back from the total you are seeing on your screen.
The average turn around time for the porting service is 2-3 weeks.
Yes, it is the same as the L99, there will be no problem doing the exchange program for yours. We ask for the return back within 30 days.
Hey Peter. We've not modified one before so it is hard to know for sure. The "LS2 style" manifolds don't flow quite as well as the LS3 manifolds, but we'd assume it would be pretty close.
The epoxy on the floors is smoothed out and installed from the outside of the manifold. It's not going to come loose and go into the ports. We have seen competitors manifolds epoxy around the rods come loose and cause a valve to hang open and hit a piston.
Hey Mike. The ones that are epoxied in are the ones we have seen issues with. The epoxy breaks loose and goes into the engine. We heat the tip of the rod, run it through the back of the manifold and epoxy on the outside. The screws on the TB side are tacked in place so will not come loose. Ours have nothing that can come loose and go into the engine.
That's a good question. Doing the rod mod and porting increases the plenum volume and that flow into the runners, then it should.
Harry,
Yes, you should be able to fit the LS3 style intake, as well as we should be able to modify yours!
Thanks,
Malcolm,
We have not developed one to accept the 102mm TB yet!
Thanks,
GPI Team
Rick,
I'm sure we could work something out, give us a call at 501-985-4947, or email at support@gwatneyperformance.com
Thanks,
Sergio,
Thanks for reaching out! A painted intake manifold, although otherwise stock, would not be an acceptable core return!
Thanks,
GPI Team
Thanks for the question! The GPI Port-mod Intake will not require additional tuning. However, the ported throttle body could require calibration adjustments.
Thanks,
GPI Team
Joseph,
Thanks for the question! The modified intake will still vent the same, you'll still hook the EGR hose up at the same port!
Thanks,
GPI Team
We sell a large volume of the LS3 Intake Manifold Mods (of which a good majority of them are daily driven) - with no failures that we are aware of.
Unfortunately there are several differences between the LS3 Intake Manifold and the L76's. The Intake Mod cannot be performed on the L76 Intake Manifold.
We can either modify the LS3 manifold on your car - by selecting the "Mod Mine" option on this page, or we can send you a modified LS3 Manifold, and you could send us back your LS3 Manifold as a core - by selecting the "Exchange" option.
If you have any questions, feel free to email us at support@gwatneyperformance.com or call the shop @ (501) 985-4947.
No issues with the Intake Mod and Nitrous. They have proven to hold up very well when used in combination with nitrous setups!
Have a question about the next step of your build, a product, the status of an order, or anything else? Here is the place to ask! I’ll funnel your question to the correct team.
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Ramond B. (verified owner) –
Throttle response great
Travis H. (verified owner) –
Great service and great quality
WILLIAM TYMINSKI (verified owner) –
Looks beautiful…can’t wait to prove that you don’t need a $1500 Intake set up to run single digits!
Eric R. (verified owner) –
100% worth it. Couldn’t be happier with the intake
aden b. (verified owner) –
Great Service, quick shipping. I needed the product by the end of the week – Ordered Monday, shipped Monday, in my hand Thursday. Packed wonderfully, and the product is awesome
Jathan Powell (verified owner) –
Gpi done a killer job. Big difference
Anonymous (verified owner) –
Intake worked much better than expected. Did not dyno but from 2k through 5k rpm pulled a lot harder than my stock intake. Manuel trans,TSP longtubes w/hf cats, cold air, vmax throttle body, and npp cat back. Did have a couple issues but no problem to work out. I had to drill out the smaller vac line out in the back and the extra heat shield I bought didn’t allow the intake to lay flush in the valley. Torqing down the bolts may of worked, squishing the insulation down on the valley bolts, but I decided to trim out just where the bolts were, using the indentation from them in the insulation as a template. Worked great, laid flush. For the gains its worth every penny. Love it, thanks GPI.
Kristopher Carson (verified owner) –
Nice work port job looks good thanks!
Shane Peters (verified owner) –
Awesome results, trapped almost 1.5 mph faster on my bolt on only C6. Great product, highly recommend!
Anthony Skinner (verified owner) –
Will answer any question you need to no about any part and will give you the best output on anything you need help with
Lesley Chillson (verified owner) –
Love it got an increase in torque with my big cam
Cristian Navarro (verified owner) –
Kevin G. (verified owner) –
Great company order was done in three weeks even during a pandemic. Hope to see good gains once i install it.
Nahuel C. (verified owner) –
Great company, great customer service. Really gave me exactly what I was looking for and had a fast turn around time.
Michael Colombo (verified owner) –
Very professional job. My Butt Dyno is pleased. Excited to see what kind of numbers I get on the Dyno! Customer service is also great 👍
devin (verified owner) –
Picked up 11 hp and 11 ft lbs of torque peak power. In the midrange it picked up 15 on both
Rusten Bredeweg (verified owner) –
Intake was clean and in good shape. Everything looks like good quality.
Anonymous (verified owner) –
Good
Christian V. (verified owner) –
Shipped them my manifold very nice quality work came cleaned already and ready to install once received from getting the radius rods installed from them #TeamGPI
Jeremy Stokes (verified owner) –
I’m extremely happy and impressed with the craftsmanship of the intake! I’ve yet to get a retune but i can feel a good increase in the mid to upper range. Also throttle response is way better. My tuner suggested I go with a expensive aftermarket intake because the factory one was choking out my stroker LS3 but the rod mod ported intake is doing a great job for a fraction of the price. Now on to the customer service. These guys are hy far the best in the business with answering questions and keeping you informed. I highly recommend this product and doing business with them!
Kevin Wright (verified owner) –
Awesome work!
Nicholas C. (verified owner) –
I ordered the ported rod mod intake with heat shield. The packaging was top notch and so was the craftsmanship, it was a quick easy install and even before I had my tuner update my tune for it it pulled harder in the mid range. Best intake for these cars ever made period.
Lakeivier Howard (verified owner) –
Great work
ivan m. (verified owner) –
Once installed you feel the difference it’s making already definitely worth it
Johnny LeBron (verified owner) –
I spent half of what I would of spent had I bought a new manifold from on of the many companies out there. GPI’s ported and rod modification is well worth it, my speed shop was impressed by the results they saw. (Disclaimer I am pretty much full bolt on.)
Juan T. (verified owner) –
I am impressed with the performance gain over the stock manifold. Thank you
Anonymous (verified owner) –
I went into this expecting no more than 5-10 horsepower, as I don’t have a cam (full bolt-ons otherwise). With that minimal difference, I was expecting the manifold to be like the Roto-Fab, a placebo effect at best, with no real change to seat-of-the pants feeling. Simply put, that expectation was wrong.
The first thing I noticed was the throttle response. Absolutely incredible, adding to the already significant gains in throttle response the VMAX made. Touch the pedal and you go. No lag at all anymore. There was such a difference that it has messed up my gas-to-clutch timing and my rev-matched downshifts. The money spent was worth it for this level of responsiveness alone.
What surprised me more is the low-end grunt as I haven’t seen any dynos that start very low for this intake. I don’t really feel anything more in the 4k+ RPM range, nor did I expect to. Under 3k though, the power gain is MUCH more than the 5hp I was expecting. I’d liken it to the gains felt when going to headers or a tune for the first time. Very, very pleased with this extra power since 95% of my driving is in this range. Combining the throttle response with that additional low end power gives the SS sedan a sense of urgency it hasn’t had before.
My manifold was rod-modded and ported and had already had the runners ported by another company previously.
Brandon Grimm (verified owner) –
Very satisfied! Quality of the work is great and the customer service is great also! Ready to see what numbers I put down soon.
Michael G. (verified owner) –
Put the intake on today, very happy with the quality of work,and the results,car felt more responsive. Even sounded better at full throttle. Excellent customer service.
Omar Alansari (verified owner) –
Really helped with the top end power band and woke the car more
ramos.o.javier –
Great product.
NickMac –
This is awesome piece of work. Really helps the cam do its thing. With the SS4 and rod-mod my 1le put down 489 hp and 441 tq
Chris (verified owner) –
Very impressed! Made a noticeable improvement at the track!
Was almost 2 tenths quicker than my previous best pass. Trapped 3mph faster also.
Elio (verified owner) –
Mark Buffington (verified owner) –
I recently installed my Gwatney Performance Rod Mod ported intake w/heat shield along with my Gwatney Performance ported throttle body. Also, the air intake was replaced with a Vararam tune model. This threw the tune a curveball, and it was tuned on a Mustang dynamometer which is known for being stingy with the numbers. The 2010 Camaro L99 has a TSP VVT3 cam, AFM & DOD delete, 1 7/8′ longtubes, high flow cats, X-pipe, 3″ Borla system, GPI Rod Mod intake, GPI ported throttle body, Circle D 3200 converter. The engine has 95,000 miles on it. Results : 445 rwhp / 437 rwt. The torque was 400 at 2,000 rpm, and peaked at 4,750. Horsepower peaked at 6,000 rpm.
Skid Garage (verified owner) –
Great product and service!
tyler_haider (verified owner) –
Added 10whp to my L99 with this and the porting, adds very noticeable throttle response.