I currently have an RB5 with de-cat Scoobysport centre. The (standard) downpipe and backbox will need replacing in the near future. I don't want to have to change exhaust parts for the MOT so a system with a high-flow cat seems to be the way forward - but they are expensive.
I was thinking along the lines of an H&S downpipe (with cat) and H&S backbox. However looking through previous post some people are using P1 downpipes, or recommending Milltek & Power Engineering products.

Qs

Cat in centre-pipe v cat in downpipe?
Anyone running an exhaust with a high-flow cat?
Recommendations?
Remap?
onder2:

 

Hi
I have an 05 WRX.
Have fitted an AEM cold air induction kit, Magnex cat back exhaust & Milltek high flow cat.
These were all fitted before the car had done 1000 miles - so it was still very tight.
biggest difference came after fitting the Milltek high flow cat.
Car really pulls above 5000 rpm - specially in 3rd gear.
Milltek is quality product - although a bit tricky to fit - even on a new car!
Cheers!
Steve

 

another vote for the Milltek sportscat,as well as a nice performance boost, gives my car a nice hard edged growl when on full boost. mines a 2002 wrx, sti up-pipe, milltek sportscat, tsl mid-section & tsl group n backbox.
Just had its first mot & emissions were very good, tester was impressed.

 

Had a long hard look at a Miltek sport cat DP at Powerstation last week, nicely made and a quality piece.
I was told the matrix was 75 holes/sq inch, most are 100 or even 200. (the lower the number the less flow restrictive)

Graham.

 

I'm running a Graham Goode Sports (100 cell) downpipe, resonated decat center and H&S Bbox.

The closer the cat is to the engine the hotter it gets so the better it works. Catted DP's generally have better emissions characteristics than Catted centers, but at very high power levels can be restrictive. For a long while H&S didn't do a sports cat centre as they were concerned about it passing emissions.

With a remap my MY98's pushing about 275 brake and 275 lb/ft with this exhaust. Not been MOT'd yet, but during the tuning process the emissions looked pretty good.

Mike

 

Thanks for that. Unfortunately a Milltek sports cat DP will not fit on my car (although they tell me that they are planning to develop one that will). As far as I can tell that leaves me with choice between H&S (ending up with a full H&S system) or a Graham Goode (ending up with a system v.similar to Mike P).