GSR/b16/Type R FTW...But a stock LS tranny can handle 350 hp all day...its your drivering skillz that will rip the tranny apart....You will have to replace 3rd an most likely 4th gear also...replace the bearings, an synchro's at the same time...DO NOT replace just the synchros you will have a problem in the future, an I bet the 3rd gear is all ready rounded off...if not chipped...an if your planning on doing this..GOOD luck I bet you will end up paying a shop to fix your screw up...Not to mention if you mess it up most shops, well mine atleast will not even try an fix your screw up, b/c no telling what you left out or did...So good luck