How much horsepower can the Impreza wrx transmission handle?

about 330 whp taking it easy on the launches since the older ones have glass tranny's

Yeah it all depends on driving habits. If the car is just a street cars & only driven hard occasionally on the freeway then it will handle a good amount. Launching will only break first gear if the clutch is dropped at too high an RPM. If u let out the clutch quickly but not instantly at around 4500 to 5000 u can launch beautifully without doing too much damage. Also letting the clutch out too quickly into third gear can be a problem. When u shift at red line to third u r dropping RPM is to a place where the engine is making a lot of torque & if done too quickly the shaft with third gear on it flexes ever so slightly causing the gear to pull away enough to cause teeth damage leading to failure. All these things can happen in a stock car to a heavily modified car. It is just a matter of learning not to shock the gears & letting the clutch do what it is designed to do. There r plenty of 350+ WHP WRX is still using stock gears around here. If you're really worried then one option is to switch to Legacy GT gears which r a little stronger than the WRX ones.

if its the 02 or 03 it can barely handle the stock power. and if your dumping the clutch and launching hard.. it cant handle the stock power.

Agreed. We need to know what year.

Dont override the 02s or 03s. l had an 03 and it went BUHBYE after upping the horsepower. They cant handle it. But 03s are POS anyways.

If u r talking a OEM WRX (non-sti), u probably looking at about 400 bhps. However, of course, how u can make the 400 bhps to the engine without modify the car, that will change the setting. Last time, we tried to replaced the existing Turbo to a bigger turbo (without stage modification) the engine to 350 bhps, the first thing blow out was an engine seal & forced us to stop. The transmission still runs fine after fixing the seal.

If u can mod to 400 bhps, the first thing it will break down probably your, engine block seals, & possible the axle shafts.

It handles 400+ hp with stock block thats for the engine, for the transmission well is weaker on the 2.0l models, but the newer 2.5l have better trannys and handle more boost and hp. There some 450 hp running stock tranny, but aftermarket clutch. Hope this helps