we installed a drag3 turbo kit on my buddies 99 si and it was boosting fine 2 days ago yesterday a bolt on the manifold flage came loose so i took the whole thing off including teh turbo and retightend the flange.... after reassembling everything we are only acheiving 3 psi of boost when before we had 6 at 6500 rpm the gauge is reading -20 when at idle and all charge pipes are connected good....im stumped

 

maybe the flanges are not ture anymore causing a very large leak and not spooloing the turbo...has happened to us. The bolts came loose and boost was gone.

 

yes chech around the manifold,make sure nothing is stopping it from bolting up flush,i had a small lip making mine not seat right,i had to grind it down flat,it was like having a open wastegate all the time.