I just recently installed full turbo back, cat delete, 02 housing, upper and lower intercooler piping, intake, stage 3 clutch, recirc. bov, and custom open source tune.
My question to you is: What is the most cost effective mod I could do next? I've thought of exhaust manifold, meth injection, and others. I just thought I would ask yall. And if the mods require other mods to compensate note those as well.

 

without question- a good set of cams. then maybe some methanol injection (run higher boost levels) if you are comfortable running that. Intercooler upgrade a fuel pump upgrade wouldnt hurt either. You could also get rid of the MAF and run a standalone. Good luck

 

cams, bigger front mount (ets ftw!), fuel pump, and meth

 

Aftermarket FMIC before cams on a IX.