boost question
 

I have a 1995 WRX import, it was standard when i got it apart from a cat back exhaust and a bailieys dump valve, and she used to boost to 0.8 bar boost and from what i understand this is standard.
Now recently i have fitted a full exhaust system from turbo back, blanked off the dump valve, and fitted a STI TMI, not all of a sudden she is boosting to 1.1 bar boost !
Also when accellerating through the rev range the needle of the boost guage flickers between 0.8 and 1 bar until the revs reach 5000 rpm then the needle settles down on 1-1.1 bar ?
i have not remapped the car so can anybody explain why the boost has increased ?
thanks in advance !

Im assuming that its because of the items you have replaced it has let the turbo work more efficiently as the exhaust is quite restrictive when stock so the aftermarket is allowing better air flow etc... this is merely a guess and someone will be on soon for the correct answer :L

that was my guess too but just wanted to check !

and how easy was the tmic to fit?

Have you done a decat?

it was a v2 STI TMI so size wise the same and very easy to fit, i just wanted the hard pipe and better flowing pipe that is behind

yes mate decatted

a decrease in backpressure will increase boost

thanks mate

Yeah, its because you have done a decat.

The exact same thing happened to my mates golf when he went from a restrictive exhaust to an open one, 5 psi boost increase. Amazing but true.

strange as thinking about it i fitted the exhaust a few weeks before the other mods and still boosted till 0.8 until i fitted the other mods

Prehaps you had a boost leak before :nono:

yeah that though went through my mind too !!!