boost surge

[thumper]

Alright here is the problem. This happens in second and third gear havn't tried 4th. I've turned my boost controller down to 10lbs just for diagnostic reasons. I step on the gas WOT. My boost comes up to 10 psi it holds strong untill about 4K then it just continues to surge upward towards 20. I let off the gas by 17 psi as i'm afraid of what may happen. According to logger I'm still running ok untill about 5k where knock comes in usually still increasing counts when i let off (17). I would relate the knock to too much boost. My question is why has my boost started to soar. It started doing this after i put on my 3" exhaust. No o2 eliminator. Do i need to get a 34 mm flapper? I'm confused witha bigger exhaust i thought the flow would be free'er, and it seems like the flow has decreased.

91' Eagle Talon Tsi

setup-
190lph
stock injectors
stock fpr
K&N
3" home made intake
silencer removed, but not lower honeycomb
mbc set at 10 psi ( i use to be able to hold 15 psi fine)
3" turbo back system
no cat
stock o2 housing
stock exhaust manifold
no port work

 

[EclipseTrbo420A]

sounds like you have boost creep. with the exhaust the turbo is now flowing more and the wastegate hole is still the same size.....try porting it out the 02 housing and the wastegate hole...that should help or get an o2 dump. good luck.