Phil WRX 01

I orderd a 2nd decat section for my 01 wrx today.
When fitting do i replace the cat sensor with a blanking plug or do i just replace with existing sensor ?

Will I need a new gasket for between new decat and downpipe?

Will I notice power gain ? Magnex backbox and mid section already fitted .

steve_g

I would be interested by any replies to this as I am replacing the centre section and 2nd cat on my car today.

As far as I know the lamda sensor gets screwed back into the new straight through pipe. I don't know if you get an engine warning light or not but I'll find out today when I get mine fitted. I would have thought that the cat in the downpipe would prevent a CEL

steve_g

Just to update you. I've had the decat pipe put in where the 2nd cat was and the centre section replaced. The lamda sensor screws into the new pipe and I don't get a CEL

Markyboy uk

I may be wrong, but I think thats because the lambda in the centre pipe takes it's exhaust gas readings before the final cat (as it is positioned just before the last cat in the exhaust). If you took the cat out of the downpipe then you (eventually) would get a CEL on an MY01...

Does the centre cat removal make much difference to performance?

Buzzer

I think its around 18bhp for a centre and back box. A full de-cat should be around 35bhp...............only 5bhp is through doing the up pipe but jeez it doesn't half spool up quicker

steve_g

I'm just about to go and give it a good thrashing to see if it pulls any better. It doesn't appear to spool up any quicker but then I do still have the downpipe cat in place.

Markyboy uk

I changed to decat downpipe a few weeks ago - that DID make a difference. Pulls much better.

Buzzer

The downpipe is the best gain you will get out of any part of the exhaust mod. However as i said the spool up time from the uppipe being done is just as good a mod as any

steve_g

The car seems to pull considerably harder. It now pulls cleanly all the way to the redline. It used to begin to die off over 6,000rpm. The boost doesn't kick in any lower down the rev range. I think a sports cat and re-map would really change things.

Buzzer

Oh YES

Phil WRX 01

Cheers for ur help guys ,the decat arrived today so i should get it fitted this weekend .

Does it make it any louder ?

Did u need to replace gaskets ?

Buzzer

My gaskets weren't changed but then the car had only done 10,000. I would say if they are cheap enough, replace them. Oh and yes a lot louder.......well at least a lot raspier. The car will give out a slightly louder and considerably more tinnier type sound. When you get the down pipe done it will sound very different and then you get a strong whistle from the turbo when you get the up pipe done

Nice though

steve_g

I reused the gaskets they were in good condition. The car is only 8 months old though (11,600 miles).

We even lifted the car back in the air whilst it was ticking over and all joins were perfect.

I had a mate help me who works at a kwik-fit so we were able to get it up on the lift. Makes it a whole lot easier.

It's a lot louder too. Much more of a roar on full boost and a very deep rumble at lower revs. I have removed the centre resonator though so this may be responsible for some of the noise increase along with the removal of the 2nd cat.

Phil WRX 01

Thanks again guys .

I just can't wait to get it fitted and go for a drive .

Cheers Phil...

Markyboy uk

What size spanner or socket do you need to get the lambda out of the cat pipe?

Mark

Buzzer

Bloody big pair of mole grips

The thread gets coked up and is really difficult to shift

Steve vRS

Backbox and centre sections will give you maybe 5bhp if you are lucky. The downpipe is the big gain, maybe 30bhp with the other sections. I didn't notice any difference with the up-pipe which was a p!sser as it was the most expensive and difficult to fit section.

Steve

Buzzer

Steve

I've always used this when quoting gains. I must admit i do find it hard to believe anything more than 20 bhp in total myself but i'm sure they've done their tests