Hello,

Just wondering whether a decat on standard 2.25" exhaust would still give good gains. As I understand the most restrictive part of the standard exhaust setup is infact the downpipe IIRC. I know in order to get the most of it would need a full turbo back but would they be any problems in doing so.

Open to opinions even if I'm been silly.

I fitted a 2.5" decat downpipe and I'm convinced it made a difference over the restrictive standard one.

Thanks for that Rob. Did you need an adapter or anything to fit to standard exhaust or just clamped it? Just had baby not long ago so if it's too loud will ahve to put standard exhaust on and take my 2.5" cat abck off. Was hoping for performance increase still but with oem look.

Thanks for that Rob. Did you need an adapter or anything to fit to standard exhaust or just clamped it? Just had baby not long ago so if it's too loud will ahve to put standard exhaust on and take my 2.5" cat abck off. Was hoping for performance increase still but with oem look.

It needed a 2.5" to 2.25" adaptor to clamp to the standard system.

My decat DP has a small resonator in place of the cat and it doesn't sound much different from stock. Definitely no louder in the cabin, just a bit deeper note when flooring it.

it won't pass an MOT without a cat, even if the emmisions are within the specified limits

No emissions testing in clean green New Zealand

No emissions testing in clean green New Zealand

lucky bleeder i had to have a sports cat welded into my de cat DP :'(

it sounded excellent with the miltek non res system aswell!

i think i'll be having a removeable/interchangeable de cat pipe put bk in so i can swap n change at mot time :yes:

yeh thats what i.ll be doing swapping at mot times. So do you get more performance without cat than even if a sports one was installed?

They say that the cat itself is not restrictive it's the downpipe.

So you can get the cat welded into a 2.5" downpipe and still get the same gains.

Thanks for that Rob something worth thinking about. Another question while were on the subject does the car through a wobbler and show the CEL light? If so how do you remedy this? I've heard of wayne angle blocks been used on mk4 golfs but nothing i've found on here. Also a company called 42 drafts do them but out of stock typical.

I had a Wayne angle block ready to go but in the end I got Ben at Shark to map out the code when he did my stage 2 map.

I hear the spacers do work without throwing codes though.

where did you get your angle block from? No companies in uk sell them :(

my de cat didnt have the chamber in, and the gains were noticeable straight off. both noise and performance wise, since fitting the sports cat there is a noticeable loss in both but not a great deal

Edited 1 September, 201015 yr by sivrs

How did you get round the CEL mate, same way as Rob or something else. The one i'm getting is in two pieces with no chamber as you put it.

it was mapped out by ben@shark performance when he did the map

You stage 2 then or 1?

was stage 1, but took it off to put it all bk to standard ish to sell.

now its stopping i think so will go stage 2 i hope

where did you get your angle block from? No companies in uk sell them :(

I emailed Wayne on the US - the guy who makes them:

wayne92slc AT yahoo.com

Got quick response and paid via Paypal

I've never had a CEL for my decat.

really thats lucky. Was the decat fitted before or after the remap tho. Just wondering whether rtech have mapped the signal readings to fool ecu into thinking cat is still working properly.

How hard is it to remove the O2 sensors from original downpipe? Any special tools or any tools that might help other than the usual stuff.

Just a decent spanner - 19mm IIRC. I was using an adjustable one and I couldn't shift it. Borrowed an open ended spanner off a mate and that did it straight away.

Cheers Rob will give that a go, just dont wanna brake my sensors cant imagine there cheap to replace haha

About 40 quid off Ebay IIRC - I thought my front one had gone, but turned out it was fine and I needed to swap the two over in the decat because the design of mine puts the front one in the silencer and that confused the ECU.

So I have a spare now!

well i.ll let you know if i need one bud hope not. Mine is a 55 slave and yours a 04 so hopefully will come straight out like yours. Heard about earthquake in new zealand hope you weren't affected.