my brother is working on 170k

the na motors are good till something goes horribly wrong.

and your s5 NA has higher compression rotors, so turbo is not the smart thing.

if you wanna go turbo, your best bet would be a s5 TII motor, and just do the swap.

and you could always go with the v8 route....ls1,ls2,ls6,or if you just loaded..ls7 the ls swap is a very common swap