How much horsepower can the 04-06 Impreza wrx transmissions handle?And will a good brand name aftermarket clutch allow more horsepower.Im only looking for about 300-400HP

the general consensus is that the 5spd transmission can hold around 300 ft lb of torque max. also this heavily dependent on the user. a moron can break the tranny with stock power levels

for those power levels u need a 6spd tranny or an aftermarket gearset like ppg gears..

big power will be big $$ & likely big reliability issues

you should also think about getting a evo ix instead. it is much easier to go for big power with an evo.. cheaper still would be a v8 american car

Yeah on a wrx tranny 300-330 would be the max l would push it and dont just flog on it cause one hard launch and its done for

you are going to have to get pretty much a racing tranny. levelten, or IPT transmissions are the best.