exhaust size?
 

Hi all, just a bit of advice needed please, im looking change my exhaust for a decat system , i have already got a deres center pipe but the thing is its 2.5 all the way through , do i just buy the down pipe and back box 2.5 or replace the full system for 3 inch, will there be much difference in power gain between the two? 2.5 to 3 inch , thanks guys

unless you are running somewhere past 400 bhp then the 2.5 inch is fine , better with a sports cat rather than a de cat mot time but your choice 👍

I swapped my standard system for a 100 cell sports cat and all 3" bore. Really increased the the power delivery. Can't say if it would be much better than a 2.5" system. And as said go for sports cat.

i’ve got 2.5 inch on all of mine , i had a 3 inch did not notice a difference ,im running around 340 bhp , a centre section either cat or silencer delete helps the car to flow better , a good sports cat v a decat on haywards and scott’s site they state only a 2 bhp loss , on the plus no mot issues , i went japspeed 200 cell sports cat as they are not silly money , and it works fine , it’s passed its last 3 mots , as long as with any sports cat it is fully warmed before the test 👍

Yea with my 100 cell ninja cat it passes, but needs to be the temperature of the sun :cry:

So think I'm going 200 cell. Be interesting to see the power difference. Saying that I'm looking to fit new turbo at same times so might never find out.

I've got a TSL 100 cel 'Thunder Cat', (2.5") a nice bit of kit but it needs to be very hot to pass emissions. It's been on the car for 14 years and is paired with a straight-through centre section and a TSL Group N backbox.

Thanks guys for the help , i think i will go sports cat then 2.5 , and back box , VXR 2010 where did you get your japspeed from ?

an ebay job , 230£ or so a few years ago 👍

This one is for a classic

https://www.ebay.co.uk/itm/200CPI-JA...-127635-2958-0

But to be fair I think any cheap eBay is all the same.

https://www.ebay.co.uk/itm/200-CELL-...-127635-2958-0

i have found some on Ebay but they all seem to be 3inch ,

Oh yea forgot you don't want 3", try Japspeed website. What year Impreza is it for?

sorry i should have said , its to fit onto a 2005 sti widetrack

Can't see anything on Japspeed website oddly.