markwild

Is it possible to replace the '2nd/3rd' cat pipe, centre and backbox on a newage to give better power and still pass an MOT (i.e. leave the original DP only) ?

I decatted my classic completely, but getting the MOT could be a pain and the car was V. noisy.

I'm after good power gains from an 02 STI without the hassle - and without the mega noise !

I'd be looking to remap eventually, but would the car run fine (say for 12 months) with the above mods.

I'd probably go for the H&S kit, still bearing in mind that I want decent power, not lots of noise (particularly when starting and sitting on the driveway - Lots of hassle from Neighbours when I had my classic - they all cheered when it went )

Cheers,

Mark

PS _ To anyone who knows me - I KNOW I haven't got it yet, but there's no point in pretending I'll be keeping it standard

BrynO

2nd & 3rd cats would be the down pipe and centre section, I guess you mean remove the centre section cat and leave the DP and up-pipe cat in place. If so then yep, no problem with MOT the centre section is the one the PPP removes anyway.

If you are also intending to remove the back box and resornator section, just leaving the downpipe cat and up-pipe cat, I sure hope you dont live anywhere near me!

Butty

iTrader: (2)

If you keep a d/pipe cat then a sports cat from Milltek, TSL, H&S or even a s/hand Prodrive one will still allow a good power hike (350+ bhp) yet be MOT friendly.

NIck

whitto

Jesus, how many CAT's have they got on them ????

I've just bought a 2002 Bug Eye STI and was wondering about a de-cat, it has a Scorpion back box fitted which I want to keep, whats the best option ?? (but no louder !).

Also, its had a “Power Chip” fitted, are these any good and will it cope with a de-cat etc ? or would it be best with a specific re-map after mod?

Matt.

markwild

I'm basing this on :



Therefore, I'm looking to replace the cat pipe, centre section and rear silencer.

I understand ( ) that the up-pipe (not shown) contains a cat, the DP has a cat, the 'cat pipe' has 2 more cats (or maybe just one ?), the centre has a resonator and the rearbox obviously contains the baffles......

On my classic, I replaced the Headers, Up (no cat anyway on the classic) and Down pipes (1 cat), centre and rear box - but it was quite noisy at start up at 6.00 in the morning (!), so I'm looking for the 'power without too much noise' option. However, I also want to make sure that its MOT friendly and doesn't 'need' a remap immediately (obviously, one would be beneficial, but that can come later)

Guess I need to locate someone with similar mods at a show and see what sort of noise level its at.

Cheers,

Mark

shadower

Hi

i got a new centre and rear box for sale only 2 weeks old from scooby world
trading my 05 for the 06 thursday and it wont fit

Tony

markwild

Sorry Tony,

Its a bit big for what I'm looking for (your Ninja system) - I prefer the 3.5" tailpipes.

Thanks Anyhow,

Mark

555 Markus

The MY02 STi doesn't have a cat in the up-pipe. The MY02 WRX does.

I ran my MY02 STi for its first three years with just the cat of the standard downpipe in place, after changing the centre pipes and backbox in favour of a blitz nur spec R. No problems emmissions wise getting through the first mot, even though the examiner did comment on the noise levels .

Having now had the car remapped by Bob Rawle, with the standard downpipe replaced with a Prodrive sports cat downpipe, its four weeks till mot time to see if things are still ok!

Mark

GaryCat

Yes. This is what the PPP upgrade does - i.e. replace the cat pipe with a straight through pipe.

markwild

Thanks for the info

Mark

whitto

So I'm looking at either a de-cat pipe (centre'ish) section but still pass the MOT or also a de-cat down pipe (for the full monty) and not pass the MOT........hmmmmmm.

So I need to look for a new de-cat down pipe and de-cat centre section to fit onto my existing centre resonator and Scorpion back box........

(I've never liked cats.......)

markwild

Mark (555) - Just to get us hungry ( ) -

Did you replace the cat pipe and the resonator centre pipe (+b/b) ? (sounds like you did, just checkin')


If so, then how much difference did :

a) Cat pipe, centre and backbox back
b) once you'd had the map

RR'd figs would be great, but feel can do

Mark

555 Markus

Hi Mark

Yes, the blitz nur spec r is the backbox plus centre pipe. The UK MY02 STi has a two part centre, as your diagram showed. It was also necessary to get a "link" pipe (to replace the cat pipe connecting to the downpipe) as the blitz centre piece is a bigger diameter than the downpipe.... 2.5 to 3 inches I think.

For info, the JDM MY02 STi only has one complete centre section I believe.

This meant I was running the car with just one cat in the downpipe, and the resonator that is in the centre section of the blitz. That was all in place when it passed its first mot.

To be honest, just replacing the 2 piece centre and backbox, powerwise it didn't make a geat deal of difference. Noise wise, the blitz is well known for being one of the louder aftermarket exhausts available, and it didn't disappoint.

Since last May, I changed the downpipe to one from a WR1 (high flow sports cat), added a walbro fuel pump, RCM induction kit, knocklink etc, and Bob Rawle remapped it using ecutek. Haven't put the car on a RR, but Bob expected figures to be around the 325/330 bhp and torque mark. As for driveability, the torque is stronger in all gears which is the main benefit. In fifth / sixth the boost will hold at about 1.5 bar.

Hopefuly the high flow sports cat should see me get through the mot ok.

I wouldn't consider decatting a MY02 STi without a remap. There were all sorts of issues with boost spikes when the model was first modified by people back in 2002. I'm sure some more knowledgeable than myself can confirm this and how this situation was best dealt with. Changing the restrictor size perhaps?

Hope this helps. My STi can be seen here:

http://markus8581.fotopic.net/c34764.html

Mark

markwild

Cheers - Though I assume that when you say 'I wouldnt consider decatting... without a remap' you refer to a total decat.

i.e. replacing cat pipe, centre and b/b is OK ?

Mark

555 Markus

Yes, sorry I didn't make that clear. I never had any problems with just the main cat in the standard downpipe in place.

When I changed the downpipe a couple of days in advance of the mapping session Bob advised me to stay off boost as much as possible on the way to his place. On the way home it was a very different story!!

Mark