Cat Pipes

Cat Pipes

Compiled by Dot

The pipe "improves" the sound and increases performance by about 2bhp.

Posted 06 November 2000 at 09:41:09 UK time


Thought I'd report back on fitting the silenced cat-rep pipe from Moto-Build this weekend.

I did this on Saturday morning (seeing as it was dry) lying on the driveway under the car. I didn't have a suitable jack so I didn't bother with that and it wasn't a problem.

The undertray came off no problem. I've seen it done many times at dealers but didn't appreciate how long it would take without an air-gun! I sprayed WD40 all over the cat's 6 bolts and left it for a few minutes while I checked my tyre pressures. The car is 13 months old at 23.5k miles and the bolts were rusty but not badly corroded.

The bolts were pretty well stuck but after a couple of minutes the first bolt started to move and after that the rest came off reasonably easily. The last one (as always) was a complete bugger. It had the worst access which only allowed a small degree of movement at the wrench. After about another 10 minutes the last bolt came off and I was feeling rather proud of myself.

I didn't realise that I'd have another 15 minutes struggling to actually remove the cat from the exhaust system but eventually it came away and that was the end of the hard work.

The replacement pipe is just the right size and after a little messing about getting it lined up the right way and sliding the gaskets in, it bolted in in a few minutes. After this I started the engine to make sure it wasn't leaking and after it had warmed up a little I tightened the bolts once more.

The undertray went back on without a problem and that was that. All-in-all it took 2 hours to do the job.

Due to other commitments over the weekend I didn't get to drive the car for over 24 hours which was torture! But it was worth it, it sounds lovely without being intrusive on the motorway and there's more power available right across the rev-range. It also revs a couple of hundred RPM higher and 2nd gear has seen the rev-limiter more than a few times since.

It's good to get your hands dirty now and again ;-)

Tools I used:

Socket set: 6mm, 10mm, 15m, 17mm
Spanner: 15mm, 17mm
Allen key: 6mm

An excellent guide to replacing the cat bolts can be found at

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© Elise FAQ Team 2002