Turbo on the 2004 STi/exchaust on the STi

It needs to be balanced. If indeed it has 3 cats, then the uppipe cat and some tuning should offer an nice bump of 20hp at the wheels. This is why I love my Vishnu Stage 0.

Next step would be the TXS down pipe and the stock echaust. It comes with one cat (with the option of cat elimination) mated to the stock exchaust. Still pretty stealthy. A possible 20 more hp with some nice custom dyno tuning.


cheers

Nick

The downpipe cat is a big restriction. I had a catless downpipe and the response was much faster(only one high flow cat left). I would have full boost (an incresed 16.5)at 2600rpm. Then I went back to the stocker and I was like what happened... :roll:

Cheers

Nick

Well this is the deal with CARB (at least and I think fefderal laws). You cannot legally change the cat unless it mulfunctioning. So I am betting that the PPP will be for "off road use only" and Subaru dealers will not install. Also you cannot touch any of the emissions equipment unless the replacement has a CARB #. This is to make it 50 state legal.


cheers

Nick