just wondering jake,what is needed for stage 4/5?i have the 248's,shrick vgi,aquamist,green injectors,walbro,throttle bodies,v2 blower.running 8.5psi pulley.the head gasket is a copper spaced one.what safety measures are required.is it just a smaller pulley and a mapping session?cheers in advance! anorak the previous owner tried a smaller pulley[11psi] at STEALTH.vince said ther was concerns of spiking at full throttle although it made 320bhp on the rollers,he said keep the 8.5psi pulley on to keep it safe?