cat to silencer replacement ?

[Andy Bowles]

To All/.
After a full service, lot of bhp gain, handling work and a clean bill of health from Abbotts, my 9000 cse 1994 2.3T is shifting nicely: bigger back box, sports this, sports that, springs, bushes, trionic etc.blah..blah....you know the stuff.
Anyway....To improve throttle response and MPG, they have recommended replacing CAT with a straight thru silencer box. I have got a good working relationship with Abbotts, so not a problem there.
Would appreciate some practical input from anyone who can give me any personal experiences or advice.
(yes, I know the CAT is needed for MOT etc).
Over £.200.00 plus VAT plus a 300 mile round trip needs to be worth it after all !!
Thanks, Andy.

p.s; does anyone elses "average MPG" indicator refresh itself every few miles, ( around .1 or .2 at a time ) ?? currently around the 27 MPG mark !!

[anglosaxon001]

Andy,
Congrats on the mods....I hope you enjoy. I can't help you on the Cat question (my 9000 is too old to worry about such newfangled devices !), but the avg mpg display sounds ok to me.
Mine does the same, it is simply refreshing the average depending on how much (or little) 'boot' I have been using. Get a nice high avg on motorway cruising, then go using a bit of wellie round some bendy roads and watch those numbers change....lower and lower !!!
Dave

[quarryeff]

You will note with the average mpg display that if just reset it is very sensitive and might change from say 17mpg over the first mile to be reading 30mpg after another mile. This is simply a matter of averages; the further you go the more difficult it is to influence the overall figure.
The average mpg is computed every 100metres I believe. It's just that if it is some time since it was reset then the tiny changes you see are to be expected.
It just struck me; Are you aware that this display can be reset to start afresh?

[Andy Bowles]

Thanks both of you/.

It went askew after all work done, so I reset it. For a while, it went from 0.1 to 99.9, all over the place, but as you say, now settling down. on a 60 mile motorway trip yesterday, found its way up to 28 - 29, now down under 27 again !!

Will post figures after it has settled down,and replaced CAT, and got comparative reading for everyones info.
Andy

p.s:Roger,pin in tonights post !

[PIERS9000]

well, pleased to hear you are going for it, I have been running a staight through for a few weeks now, no probs so far, certainly has more ooomphhhh,let us know how you get on.

[chrisn]

Andy,
When I had to replace the down pipe, I took the opportunity to replace the CAT with a SAAB silencer box which is a direct replacement. I preferred not to try the straight pipe, to keep any intrusive noise down. All this at the suggestion of Steve at Malbrad, Huddersfield. The car is certainly a lot quicker on acceleration, and doesn't seem to become stifled higher up the rev range as it did before. As a 92 car it does not have to have a CAT, but emissions were way inside requirements at MOT. There is no additional noise in normal driving, just a little extra when you er.. press on. Oh, and the mpg improved about 2 mpg at a steady 70. Hope this helps.

9000 CS Carlsson