GTI6 Exhaust Size?

[aaddzz123]

I'm currently running a scorpion backbox and a standard mid section with a cat. It actually sounds quite nice, but the mid section has taken a beating under the rear axle and is "squashed" so I think it may be causing some restriction and I'd like to have a go at making an exhaust (I'm trying to become an amazing welder and this is my first project lol! Get ready for the bird shit seams).

My question is, what diameter would people suggest? I've only ever really seriously modified my GT and that's a turbo so, the bigger the better really, but I do understand that back pressure is something to consider with a NA? Or is that all bollocks?

I was originally going to go for a full 2.5" mild steel set up. From the manifold, no cat, no mid section and then keep the scorpion box for now, with the likeliness of making a new stainless box in the future... I'm wondering if 2.25" is more than suitable, if not better!?

Opinions and experience please

[Janne L]

2,25 is big enough for the 6s power. A smaller exhaust is also less loud, a 2,5" pipe with only a backbox would be pretty noisey.

[7057sam]

Yeah I've had booth 2.25 and 2.5

I found 2.25 is easier to live with day to day and responsive  enough  with the 2.5 it's pushing more top end but abit Laggy at 3-4 k and has a very loud 3 k drone 

2.5 is more suited to boosted  

[RetroPug]

2.25" is the right size, I have a 2.25" stainless centre section without a silencer going to a scorpion backbox with a cat and it sounds fantastic.