How Much will the transmission take?

How much with stock tramission take before breaking?

Got a 2002 GT (4 door) that I'm planning on moding to some degree. I really enjoy running it around the local road racing track during some club events.

Currently purchased a u-bend replacement and the GM suspension upgrade, they'll be added to the car soon.

After that, the plan I have sketched out is (in order of installation):

* Wizaired Cold Air Induction System with 9" K&N cone filter
* GT High Velocity Throttle Body (stage 1)
* L36 HV Intake Insert
* L36 Throttle Body Coolant Plug
* Under Drive Wapter Pump Pulley
* 10% Under Drive Wapter Altenator Pulley
* Random Technology 3" Downpipe/Hi-Flow Cat
* custom 3" exhaust with high flow mufflers
* L36 ER Rocker Arms and Install Kit
* A modified PCM of some sort (gonna be awhile :iceslolan )
and perhaps a Ported Exhaust Manifold

To the best of my research, this will add somewhere between 40 and 80 HP and more torque as well.

I know that the transmission for the GT and GTP is the same except for the final drive ratio, and the transmission for the GTP seems to hold up pretty good, so I think that I'm going to be OK.

Mind you, I'm not looking to create a drag car, but a daily driver (a sleeper) that's more fun to drive and has some get up and go to it, without sacrificing any longevity, reliability or drivability.

You think that using Mobile 1 ATF is a good idea for this? What's the downside? I presently change the Mobile 1 engine oil and filter like clockwork every 3K miles, figuring that the engine will perform better for a longer time before it will need major work to refresh it.

What do you think?

FYI - the GT transaxle is the 4T65E, the GTP transaxle is the 4T65E-HD. The HD has some improvements that give it a higher torque rating, but I can't recall the exact numbers off the top of my head.

The main weakness (there are others) in these transaxles has to do with 1-wheel burnouts. If you are doing burnouts with the stock diff then it won't be a matter of if the transaxle breaks, but when. This is true even if the car is stock.

The net is full of people exceeding the torque ratings of both transaxles with much more highly modified motors than what you plan...but beware they are also several stories of broken transaxles too.

As far as synthetic ATF, that's a highly debated topic. Some people love it in these transaxle, others say you will cause damage by using synthetics...I don't use synthetic ATF, but I'm not against using it either.

IMO...and it's just opinion, you won't gain 40-80hp with the mods you plan. If you put that combo on a dyno I think you'll be dissapointed. IMO the only way to pick up that kind of HP gain on an NA 3800 is with a hotter cam, headers, and more compression...all three if plan on picking up 80hp.

Thanks for your post.

I'm really not that worried about how much HP I'll be adding, just wanting to warm things up a bit, while keeping the car a daily driver and reliable, so your comment about the tranny may be something that I'll have to be concered with.