ok i have an 89 gt but this question is a general turbo question(as in not for my mustang lol) i have a turbodiesel truck that runs 50psi of boost. there arent any 50psi springs out there(in my budget) and i know that a blow off valve has positive pressure sent to the diaphram via the vacuum line. so even though my truck will make more boost that the spring i will run can handle, wont the positive pressure in the diaphram hold the blow off valve shut and when i take my foot off the throttle and the turbo stops building boost it will lower the pressure in the diaphram and thus blow off? this is only really part of the problem because the only reason i want to run the blow off valve is to find some way of turning my boost down as low as possible (somewhere under 5psi) in order to run a bunch of fuel through the motor and not alot of air so i can leave 400 foot long clouds of soot. i do have a wastegate but running a boost controller on it wouldnt help because i have a sequential turbo setup(tons of boost, quick spoolup) so all my wastegate does is feed the big turbo to spool it quicker. i know i should be on a diesel forum but those guys dont even know what a blow off valve is. the only one ive found for diesel applications is a 650 dollar bd turboguard that is electronically controlled via TPS. thanks for any help guys-chuck

 

not real sure on this I know my blowoff is impossible to push open until I put some kind of vac. to it. But I have not put 50# of press. to it. why not just add another wastegate?