Cat Bypass

[CaptainSlow]

So I can take the Cat off my 92 Eunos with no MOT issues. Is it worth fitting a bypass pipe?

[hornetrider]

It's great for hooning but not for cruising - its adds a massive amount of cabin boom. Horses for courses.

[CaptainSlow]

Any noticeable performance benefit?

[hornetrider]

Ummmm, not that I could tell. Maybe a bit on the arse dyno due to the noise but not really, no. Sounds awesome when you're thrashing it but gash when you're bimbling along, obliterates the stereo!

[CaptainSlow]

OK, will have a listen on the 14th.

[MX-5 Lazza]

I think it depends on the rest of the exhaust. The 2 cars I've been in with cat-bypass haven't sounded a lot different from stock, just a bit of extra growl on acceleration. It would be amplified by a louder back-box though.

[hornetrider]

Good point, I did have an MX5Parts Dual on mine

[anonymous-user]

I've got an MX5Parts twin pipe on my 92 mk1 - originally i fitted an unsilenced decat bypass but it was insanely loud, and not all that good a noise. My 2 litre barely-silenced Zetec kit car was quieter.

Now it has a silenced decat pipe from Moss and although still loud when accelerating it's a much nicer sound, and you can crawl around quietly if you want (or need) to.

It is a bit boomy cruising at about 70, but i don't mind that as the car isn't used on the motorway all that much. If you're doing longer distances at a constant cruise then it may well get annoying. How much of that is down to the twin-pipe I don't know, as I've never tried it with the cat on.

Edited by anonymous-user on Tuesday 2nd November 20:10

[MX-5 Lazza]

I think that's the MX5 Parts exhaust rather than the cat bypass though.

[hornetrider]

Mine was quite acceptable with a cat back in place though. With the decat pipe it sounded like I was on a bombing run

[anonymous-user]

MX-5 Lazza said:

I think that's the MX5 Parts exhaust rather than the cat bypass though.

Quite possibly, but i do know that the noise difference between the silenced and unsilenced bypass pipes was massive.

Edited by anonymous-user on Thursday 4th November 17:38

[CaptainSlow]

wow good timing, mx5 parts have these on offer for £43 this week, worth getting?

[MX-5 Lazza]

We have an unsilenced pipe on the PlanetMX5 Motorsports car (with a back-box of unknown origin - think it might be an old ILM or MX5 Parts) and that car isn't really very loud at all. Mind you, I'm comparing it to mine which is pretty loud lol (Larini Sports Cat, Larini Sports mid-pipe, Racing Beat Power Pulse Dual back-box).

[seismic22]

just fitted mx5parts silenced decat with standard back box. Can barely notice the difference in sound but car seems to pull smoother and perhaps feels a little more torquey higher up.

[carreauchompeur]

Ooh, this is an appealing mod... Mine's far too noisy anyway Presumably, with a '90 import, I would also be alright re MOT?

[anonymous-user]

My 92 Eunos has passed 3 MOTs with the twin pipe and no cat.

[youngsyr]

I had a listen to a Mk 2.5 with a gutted cat, but otherwise standard exhaust and MP62 the other week, it was barely, and I mean barely, any louder than standard.

[CaptainSlow]

Just bought a Magnex pipe, will fit it and see.

[seismic22]

i fitted a mx5parts silenced de-cat, keeping the standard cat back system and the increase is barely noticeable most of the time, it does like to pop and bang when ringing its neck sometimes now tho!

[CaptainSlow]

ok so the pipe has arrived. Have ordered some new gaskets but one was the wrong size to have to sort that out. Question is the cat has an o2 sensor plugged into it. What happens to this sensor when the cat bypass is fitted?

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