HI, I'm having a little problem, I'll tell you what I have.

1st gen turbo 2
s4 j-spec
to4b with big shaft and bigger turbines
680cc secoundarys
front mount IC
3"dp and full 3" exhaust
Holly 255lph external pump
surge tank and pre pump
GReddy Boost gauge
A\F gauge

I think that's it. I'm running stock Boost, but boost is creeping to 10psi in 2nd and 13psi in 3rd. the problem is it seems like the timing is being retarded at 6K, like losing lots of power, I'm just shifting at 6k. any thoughts? a little more info is, I had the AFM in the IC piping and it didn't do this, but I had a bigger intercooler and wasn't over boosting as much or at all.
then I put in the stock intercooler in the front mount postion, that's when the boost creep started, and a couple days later I put the AFM back in front of the turbo where it should be, that's when I think this started to happen. I'm not positively sure about all this, because I've just install the motor maybe a month ago and only been insuring it day by day.

 

Are you using stock wastegate or aftermarket?

 

if you're running that setup you ought not use the stock intercooler.

hell, you ought not use the stock ECU with all that :P
get some bigger injectors and a haltech/microtech/whatever and put the fmic back on.

 

You might wanna get a FCD (Fuel cut defender), if you dont allready have one, then that might be your problem.
Could it be that what feels like wrong timing is really the fuelcut on the rear rotor???
Just a basic thought, I dont know much about turbos