If you want reliability with any psi of boost upgrade your intercooler, water/meth inj etc. You want to also manage your fuel psi with a upgraded fuel pump and a fuel regulator/gauge. NEVER I MEAN NEVER upgrade your intercooler piping to more than 4 inches if your not going to turn the boost up a bit. It will create lots of lag ><
i drove rx7's for almost 4 years having to worry about reliability every time i boosted those spinning triangles.
trust and believe me bro the properly vented intercoolers and regulated fuel pressure will go along way meaning that if you can manage your temps/psi you can drive that ****er like you stole it everywhere you go.
in my opinion there is no point of boosting a lot of power specially if its your dd if it isnt reliable.