how much more power would i gain if i changed from my 3 inch magnex full decat system to a 3 and a 1\4 inch system (car is a 99 model 2000 turbo with super chip and k&n induction kit)

 

Zilch, zero, nothing.

During testing I found a 2.5" system was not a restriction up to 320bhp, the 3" system will easily cope with 400+bhp

Andy

 

Agreed, you will get nothing, in fact you will probably lose as the 2.5" system is better at your level suiting the setup more.

bob

 

I used to run a 3" BLITZs....no good, and i was runing very close to 320bhp...In the end i bought a TSL 2.5 Group N system (which is now for sale if intrested)

However with the 3" low end power was lost, and you will find more gains from a 2.5", unless you are running very high power...