By Bv do you mean bypass valve, if so then you should get new both, get an upgraded bpv and an n75 race valve, the bpv is a nessicary thing with the chip and what not but the N75 isnt but a fun addition

 

ya sry for the confusion i meant a diverter valve, not a bv. i was just wonder what the difference is, and what exatly the race valvue does if you can use both

 

two different things... the diverter valve takes your boosted and evactuates it and recirculates it into your system... the n75 race valve manages your wastegate to your turbo better giving you 1-2 psi... if your planning on more horsepower, you need a new DV becuase it will crack under high boost... the race valve isnt needed but like someone said its just a fun little extra kick