T4 straight pipe instead of backbox

[lurchio2]

Hi. I'm thinking of removing the rear box and replacing with a straight pipe. I'm after a nicer sound. Has anyone done this or heard one with no backbox. Thanks.

[antz]

Ive heard of people replacing the middle box with a straight through pipe before. I seem to remember someone said that its the middle pipe that does the main silencing and power loss, the rear silencer doesnt do much.

Im not 100% on that though

[lurchio2]

Thanks. Can anyone confirm this. Cheers.

[lurchio2]

What size pipe would I need to sleeve over the original if I cut the middle box out?

[LiamT4]

What size pipe would I need to sleeve over the original if I cut the middle box out?

Its a 2.5" pipe on the t4.

[gmain1967]

Thanks. Can anyone confirm this. Cheers.

If you're going to do anything, take the centre silencer out and retain the rear box. Or take the centre one out and put on a different back box, but don't put a straight through in place of the rear box.

[The-Les]

I cut out the middle box on mine, it didnt really change the sound at low revs and I cant say I noticed any change in performance. changing to a sports cat and jetex system however :)

[bar72]

my 98 t4's decatted, defo a bit snappier but no sound difference, do this first if you have a spare downpipe/cat lying around ;o)

[Tommy t4]

I replaced cat and silencers with 2.5inch pipe welded in situ on a ramp, replaced back box with custom built 4in straight thru rear can, the performance is better low and mid range and the noise and flames is well worth the effort lol, doubt you'd get much gains from a non turbo tho.

[Slomo]

I replaced my cat with a sports 90 cell cat and removed the middle box. Err T4 is loud :)