if you are talking about crank hp supposedly an evo ix will make 307whp (~410 crank hp) with just a TBE and tune

http://www.vishnutuning.com/images/evo_ix_stg_1.jpg

that would likely be the most cost effective and reliable way to achieve your hp goal....

also, about the subaru 5MT trans.. i have 'group n' engine, transmission and pitch stop mounts on my stock '02 wrx.. unless i am shifting very slowly and carefully it is fairly easy to shift poorly and make the car lurch during spirited driving. personally, i keep the engine power stock so that the safety margin is there. i'd rather focus on other aspects of my driving during a HPDE rather than working about not shock loading the trans. i think you should be very honest with your usage before you decide to make big power on the 5MT trans.

 

pretty much what im going with now is a V7 motor, and putting the RA gears in and im done, im fully aware of how much the 5mt is garbage i just didnt care, im on number 2 5mt but yea im gonna use my money wisely and go towards the JDM goodness.

 

ah, ic...you are going jdm 2.0L (I misread your original post, I thought you wanted to build a 2.5L ). The RA gearset should be ok with a jdm 2.0L as it makes power mid to high rpms which should be safe for the tranny and also make a pretty sweet power band.

 

no, not the 2.5l nothing against it at all it makes kick *** power, just wanted the 2.0l, alot of japanese tuners make great power in the 2.0l, Blitz made a one off twin turbo kit and made like 534 awhp on a stock block in 05. im just a fan of the 2.0l.....any ideas to replace the center diff and rear diff r180 surtrac, or the torsen diffs.

 

my understanding is that the USDM '03+ 5MT have the same gear widths as the "RA" gearset

would the OP's 5MT gearbox really be able to handle more torque/shockloading with a RA gearset vs his old OE gearset? it seems like nothing would really change from a durability standpoint

 

OP's 5mt Gearbox? The RA Gearsets are cryo-treated to make them more stronger, as far as gear ratios i know the RA's are suppose to be taller than the OEM boxes.