My previous car was an 98' Acura Integra GSR. It had a stage 2 turbo kit, front mount ecu, 1000 cc injectors, cold air intake, 2.5 exhaust with header, vtec controler, and Centerforce 3 disc clutch...
All of these mods were done on stock internals at 69K miles, and it still had bulletproof Honda reliability... I drove the car for 5 years and put 80K on it without a single problem...
With a full exhaust, full intake, a pulley kit (presumably a smaller supercharger pulley), an FMIC and a tuned ECU, you're probably putting down like 60 wheel horsepower more than stock. And the stock horsepower was what, 260? I know it would be disappointing to immediately blow a gearbox for the addition of 25% ish more horsepower, but that just wasn't the case here. Your transmission lasted for 60,000 miles with that horsepower increase -- and this presumes that you weren't racing it. It sucks that the transmission failed, but in long term driving and racing, with that much of a horsepower gain, nothing else could have reasonably been expected.
As to the Integra, the GTP made more horsepower stock than your Integra turbocharged (260 versus your original 170 -- if you added a vast 50% more power, you still wouldn't see the stock output of a GTP). If it were a real car. But it isn't. There's no "stage 2 turbo" in real life. Which turbocharger was it, and how much boost? Then, for comparison's sake, was it an automatic like the GTP or a manual like in most Integras -- if they're not even in the same class of transmission, it's a pointless comparison.
I have a 2004 Grand Prix GTP Comp G with mods, cold air intake, MSD blaster coil pack, 180 thermostat, hotter plugs, 3" down pipe, and smaller pulley kit.
My car is running great and I've done 120,000 km with these mods.
To the first comment: remove your headers; you lose too much torque to hp gain, it's not worth it.
The 3800 motors are indestructible, so keep it maintained with fluid flushed ever 5k, and you will have a reliable car :D
I have an 04 GTP with 96k on the odometer. A few minor wear items replaced. Has power and cruises great on the highway at 80. Did have an 89 FireBird Formula 350; the undercarriage rushed out because of winters around here.
If they did not get rid of Pontiac, I would buy another. In fact that is all I have owned since 1966.