Dave M UK

iTrader: (4)

I have used the search and spent hours reading about my next planned mod but most info is based on the WRX front de cat and not a UK one.

I have a 01 classic 2000uk with PPP, i have 3 questions

1. Does the uk model have 3 cats like the WRX or just 2, is it worth decatting the turbo up pipe at same time as the downpipe front cat or is it better to just decat the downpipe,

2. do i just need a replacement de cat downpipe or do i need manifold replacing too, is it all one unit and if not is it worth replacing the manifold, does it give any more power over just de catting the downpipe. Also which make of downpipe gives the most power? magnex?, blitz?.

3. i have heard by changing the manifold that i will lose the bubbling sound of my engine due to the fact that the replacment manifold would have pipes of the same length, i have been told that the impreza gets its bubbling sound from the original manifold being different lengths creating the off beat sound at idle,

Any info about the front de cat downpipe conversion of my uk 2000 would be a great help, money is waiting so the de cat will happen as soon as i get a bit more info, thanks Dave M, Stoke

RON

1. classics only have two cats as standard, first one in the downpipe, (not up-pipe!) and one in the centre section, but as you have the ppp that should only be a resonator now anyway.

2. You only need the downpipe, the manifold is a whole other issue that you may get to in time....i wouldn't bother with the manifold (headers) until a long way down the tuning line.... i have an H&S downpipe, and i ike it!

3. All true, but again, read the above!


AND, it's worth doind alittle more research, because 'some' people have had issues with putting a downpipe onto an already PPP'd car...... ie.. proceed with caution....

PhilA

other's like myself and some of the RB5OC lads have to issues. Leave headers/manifold till later.
De-cat the downpipe with an open neck pipe and put a straight throught centre section in. Maximum power gain but will unlease some noise and you will need a UK centre cat on the cheap to swap for MOT's, unless you have a friendly MOT tester.

Downpipe can be a bit of a headache so if your not a semi-decent mechanic pay to get it done.

Phil

remfanuk

what is the score with MOT's and de-cats? i have a centre section straight through pipe as part of a scorpion system from the bottom of the downpipe onwards and that passed the MOT. if i was to remove the cat in the downpipe then having no cats would mean a fail...so could a car with only a centre section cat pass an MOT?

scooby_matt

Is it the kind of job your local ATS can do, or is it wise to get a specialist to fit the downpipe?

RON

Somewhere like ATS could probably do it, but i wouldn't let them near mine..... where are you Matt... there's bound to be a scooby specialist within reasonable distance....

scooby_matt

Only 30 miles from Scoobyclinic so I know where I'll be visiting in the next few weeks

RON

Can't go wrong mate!!!

scooby_matt

Will I notice a difference in performance without a remap?

RON

Oh yeh...... and sound!!.. i now advise people to change the downpipe before they even bother with a back box!!! it's the most restrictive part of the system!!

cefski

Fitted a Scoobysport b'box and de-cat down pipe to my '01 registered '00MY non PPP UK Imp Turbo nearly 18 months ago. Catted centre is still in place.

Re. the MOT questions - a uk car will pass emissions with only a catted centre section, PROVIDED the lambda (and possibly the MAF) sensor is in good working order. My car failed emissions with the centre section alone and also with both cats in place. Passed with a replacement lambda, but only just. MAF failed a couple of weeks later, so that may have had a part to play in the poor emmissions results too.

Toying with the idea of going completely de-cat, but having a twin cat centre section made up for MOT purposes

Re. noise - yes, the car will be noisier with a de-catted downpipe plus the 'zorst note will be more rhaspy. You will probably also lose the heatshield that covers the turbo and the downpipe, meaning that the engine bay will get hotter. Noise and heat can be partly addressed with good quality exhaust wrap on the downpipe, but I'd recommend that you apply this BEFORE you fit the pipe to the car. It's a bugger otherwise.

Kev

RON

The heatshield over the turbo needs cutting and re-fitting, it's very easy to do, and Scoobyclinic should be more thahn capable....

I have a twin catted centre for mot purposes.....

scoobfan

Unless you drive a Wagon, only one CAT and that's in the downpipe.

Rob

RON

Rob, i'm sure thats not right, unless it's an import of course.....

scoobfan

Ron - I'm sure that goes for all Wagons, UK/EU/JDM.

Certainly JDM, if i'm wrong about the UK/EU.......my appologies !!

Rob