Gto
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Teching In
Joined: Nov 2024
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Gto Good morning,
I am needing some advice, I just bought a 2005 GTO w/ 29k miles on it, bone stock with an automatic. I am just looking to make it a fun street/strip nothing crazy. I am not looking to change any internals at this time just some bolt ons.
Intake and TB: port and polish or buy new?
Exhaust: installing LTH, NO CATS and mufflers, what is everyone doing with the O2s? Deleting upstream and using the down stream or?
One piece drift shaft ordered, looking into dropping entire rear chassis and upgrading all suspension and bushings.
cold air intake and a tune, anything else or suggestions. Thank you
I am needing some advice, I just bought a 2005 GTO w/ 29k miles on it, bone stock with an automatic. I am just looking to make it a fun street/strip nothing crazy. I am not looking to change any internals at this time just some bolt ons.
Intake and TB: port and polish or buy new?
Exhaust: installing LTH, NO CATS and mufflers, what is everyone doing with the O2s? Deleting upstream and using the down stream or?
One piece drift shaft ordered, looking into dropping entire rear chassis and upgrading all suspension and bushings.
cold air intake and a tune, anything else or suggestions. Thank you
TECH Senior Member
Joined: Jun 2016
Posts: 22,289
Likes: 3,615
From: Central Cal.
RE: O2 sensors. Delete downstream sensors, keep upstream ones functional.
The stock TB is big enough to feed your present setup. No gain going bigger.
A FAST intake would improve on the stock LS2 unit, but not cheaply, and not a huge increase.
TBH, the only way to meaningful power increases engine-wise is a cam swap. These engines have it good everywhere else.
Headers WILL help, along with cat deletion.
The stock TB is big enough to feed your present setup. No gain going bigger.
A FAST intake would improve on the stock LS2 unit, but not cheaply, and not a huge increase.
TBH, the only way to meaningful power increases engine-wise is a cam swap. These engines have it good everywhere else.
Headers WILL help, along with cat deletion.
If you are not making any significant power increase, there is no reason to go to a 1 piece shaft. The theoretical help with wheelhop does not really happen, and it has no other benefit. It will, however, cause clearance problems you have to fix with many aftermarket exhaust systems, as well as a rear seat bolt, and it will lower your top speed. Even with a 3.5" aluminum 1 piece, I am limited to around 160mph because of the critical speed of the shaft, and MANY of the 1 piece replacements had balance issues aside from the lower critical speed. In my case I had to change it, because back then the upgraded 2 piece shafts did not exist yet, and making over double the factory power with a m6 is hard on driveline parts. And please don't put in those muffler delete pipes that used to be popular. They sound horrible and drone.
Thread Starter
Teching In
Joined: Nov 2024
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Ty, the carrier bearing had been dry rotted so bad for so long, the only thing left was the housing. The car has been sitting in a garage for almost five years and the 76 yr old man that had it didn’t know. I read about the bolts, I was hoping to simplify things with 1 piece. I was just deleting the cats, I was planning on using Borla mufflers
And no matter what condition any of the bushings are in, definitely change the front radius rod bushings first. They were badly inadequate from the factory. The rest of them is a matter of personal preference until they wear out or dry rot. Just something to keep in mind as the mod expenses add up. Also, check the bcm wires under the dash. The factory arrangement allows them to rub on a sheet metal edge that will eventually damage them if not protected. And check the fuel line under the fuel rail cover on the driver side. Some of them rub against the rubber and can eventually rub through, potentially causing an engine fire. Some modifications were made on later builds, but it is best to check.
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You should do some reading on ls1gto.com. The site went to **** years ago, but it still has a few of us original gto owners visiting occasionally. The oddities specific to these cars are numerous, and that site has the best archive of such info.
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How do they respond to a higher stall converter nothing crazy but maybe like a 2,500 stall or a shift kit? I know you want to keep external but sometimes the real pop is internal modifications.
Thread Starter
Teching In
Joined: Nov 2024
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I agree, but the main reason for not changing the internals was for resale value. I couldn’t pass up the car but my main goal was to drive it for a short time and continue looking for a late model Camaro that I can put a procharger kit on.
If you only install a higher stall with no supporting mods, the transmission will not last long. At minimum you need an extra trans cooler for the heat, and preferably other upgrades. A coworker years ago put in a Yank that I believe was around 3200 or so stall with no supporting mods. His transmission was burnt up in a matter of months. It is a 4000lb car with a 6.0. Lucky for him he had a friend at the dealership who was able to "ignore" the aftermarket converter and fix the trans under warranty.
10 Second Club
Joined: Nov 2005
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The rear subframe bushings will help a lot with wheel hop. Get the solid ones or at least urethane.
The throttle body is a good one but you can smooth the airflow a little by smoothing the ridge just before the butterfly. Do not make the area around the butterfly any larger---it will give your tuner problems on idle.
A shift kit is always a good thing. If your tuner is good, he can firm up and quicken the shifts in the tune---and---look at the write up by Cool Aid on the LS1GTO forum. Make sure and change the old fluid and filter.
Probably new plug wires with heat boots for the headers.
And like gametech said, cut off the seat belt bolts flush or the driveshaft will hit them.
Once you get the rear subframe bushings installed, with the driveshaft out, car level, measure the angle of the trans output shaft. If it is 2 degrees down, make the pinion on the diff 2 degrees up. Diff is probably pointing down which creates vibration. Get the two angles within 1 degree. Don't be lazy. There are 4 big bolts that hold in the diff to the subframe, you can shim under those to change the angle. Most people skip this step and then complain about vibration---or cancel that one piece and get a good two piece D/S.
Good Luck, Have Fun
The throttle body is a good one but you can smooth the airflow a little by smoothing the ridge just before the butterfly. Do not make the area around the butterfly any larger---it will give your tuner problems on idle.
A shift kit is always a good thing. If your tuner is good, he can firm up and quicken the shifts in the tune---and---look at the write up by Cool Aid on the LS1GTO forum. Make sure and change the old fluid and filter.
Probably new plug wires with heat boots for the headers.
And like gametech said, cut off the seat belt bolts flush or the driveshaft will hit them.
Once you get the rear subframe bushings installed, with the driveshaft out, car level, measure the angle of the trans output shaft. If it is 2 degrees down, make the pinion on the diff 2 degrees up. Diff is probably pointing down which creates vibration. Get the two angles within 1 degree. Don't be lazy. There are 4 big bolts that hold in the diff to the subframe, you can shim under those to change the angle. Most people skip this step and then complain about vibration---or cancel that one piece and get a good two piece D/S.
Good Luck, Have Fun
IMHO, a shift kit in an otherwise stock 4L60E is asking for trouble. Many posts, my tuner, and magazine articles support this viewpoint. I can't compare apples to apples, but I can provide some background and facts. I have a totally stock 4L60E in a C5 Corvette. I have about 147,000 trouble free miles on it. Let me say upfront I may have the best stock 4L60E GM ever assembled. Now for the facts. I installed a Yank 3,200 stall converter, with B&M cooler at approximately 45,000 miles. At 60,000 miles I installed a built LS7 with approximately 620chp. I have never had any trans issues. So, not all are junk. But I have to state my experience is not normal, and I think everyone will agree. My tuner altered some things. It shifts quicker, and he reduced TM, but DID NOT ELIMINATE it. He stated removing it totally is a bad idea. He also said installing a shift kit without going inside the trans to modify internals was also a bad idea. Now, you may argue the shift kit issue. What you can't argue is the trans has lived. I've even run wider, 10.5" wide rear wheels so I could fit 315-30-18 Michelin PS2s. Probably the 3,250lb weight has helped a lot. So has not running really sticky tires. As always, YMMV.....
