I have been playing around with a few exhaust systems and i recently modified a existing aftermarket into a bypass exhaust, catted and straight out the rear.
Very brutal sound with great quick spooling but now i have encountered a problem.

Does this exhaust affect the ecu or boost without a tune?
Now my car is running at 0.6 bar is sport mode which is half of what it should.

I only have headers and AP recircs with no other mods.
Maybe i have a boost leak or something but can't find it after 3 days looking around and tearing it down.

Any ideas would be very helpful.

 

I wouldnt recomend running bypas on stock vtgs, u r basically exhausting ur turbos doin that even though the small amount of bypass runners have tuned ecu's at least. U might want to datalog ur car to check actual boost vs timing

 

So it is catless straight pipe or what??