I've searched but couldn't find what I was after so I' apologize if this has been covered. As per title, want to know what kind of power gains I can expect over a stock O2 housing and stock downpipe after fitting the Tomei Expreme O2 housing and downpipe?

Car is an Evo 8 with stock turbo, 3" cat back and will be retaining the stock cat for now.

Thanks

 

I can't nor any really tell you what you will make with adding it. The who thing is to free up the exahust gas and if you do that I would look into a HFC and get rid of the stock one. The HFC wont be as restrictive and I know UR makes real nice ones out of stainless steel. I had one and sold it as I have a gutted cat and use it for my inspection.

 

get a mil.spec 100 cell hfc if you decide to get an o2 housing and downpipe

 

Thanks for the advice guys. I'll grab the 02 and front pipe, then grab a HFC as soon as I can followed by a fuel pump and a tune. Should make some nice gains over stock.