My MY00 UK Classic is completely standard. Would it be a complete waste of money to remove one of the cats but leave the rest of the exhaust as it is. The car is fitted with a standard STi back box so is quiet, would it be much louder with a cat removed. Which cat would be the best to remove, the replacement sections for the center section cat appear to be the cheapest.

Finally would a replacement air filter element make any difference to the car with or without a cat removed?

Thanks folks I am a bit of a novice in the scooby world.

 

Hi There,

No, it wouldn't be a waste of money if you just removed one of them. However, the effects are different depending on which one you remove. If you decat the Downpipe, you'll notice the greatest performance gains, but you'll also struggle to pass the MOT emmissions with just the centre pipe cat in place (you'll need to have the car tested whilst it's very hot). If you remove the cat in the centre section, you'll notice a significant change in the sound (deeper and louder) but only a mariginal gain in performance. The MOT will not be a problem.

The ideal solution is to do what Ive just done and get a hi flow DP and then decat the centre section. You get the best of both worls and remain MOT friendly. Hi Flow DPs are expensive though. Scoobyworld have an excellent offer on the Ninja one at the moment.

Air filters have a marginal effect; I doubt you'd notice the difference between a std and uprated one... unless your std one was past its best.

Be quick if you want a deal on the sports cat DP!!

Ns04

 

Decat the down pipe first, I still run mine with centre cat and have no emmision problems.(MY2000) Although legislation could change in future,so high flow cat maybe better longterm view esp if keeping car for a while and therefore a wise investment.
I do not how "high" flow they are!!!

 

I have a twin catted centre section on mine.....



Sometimes!

 

H&S reckon on about a 2bhp loss over a decat DP. A hi flow DP has a 100 cell cat, the original is 600 cell.

I have one on mine. Read the thread here:
http://bbs.scoobynet.co.uk/showthread.php?t=493962

Ta,

Ns04

 

My mate is running a standard impreza with a sti panel filter and a sti backbox, and he is running at 230bhp.

I would agree with the above comments, definatley get the centre de-catted (it only costs about £70). Your choice on the downpipe !