i got my j-pipe rewelded but i still get low vac at idle... the MBC is set at 17.5...vac at idle is near 10 psi or lower sometimes but when i rev it the vac will fall down to 17.5 then back up to 10 weird..i checked all couplers and reducers retightened everything....still low vac at idle anyone know whats wrong??? what to check???
oh yea and i keep hearing this hissing sound coming from near the injectors

Remove the Injectors and replace the seals on the head side of the injectors.

you don't have aftermarket cams, do you? Do a boost leak test.

We did a boost leak test for him a few days ago and found enough leaks that they had to be fixed to find the rest, I would guess corey is right, the injector insulators can go bad and leak. If you want to bring it in again, we can check it to find out where they are now.

Throttle Body Gasket? I haed a massive leak on mine one night, everyone stared as I went buylike I had a semi turbo on my car. :lol:

i will try replacing the seals...and i need to get the lower IC pipe reweled too