Well that didn't work, so now what?! (exhausts)

[IanLWarrington]

IanLWarrington said:

No need to pay that sort of money - I had a cat back done on my silver VXR at this place http://www.jpexhausts.co.uk/ - £600 and a lifetime guarantee - not too loud but that was my choice (had only the centre box left out). They will do what you want. Beautiful job. Have a look at their gallery.

In fact - just had a look myself and there's my old car! Not very good picture though.

[granada203028]

Lil'RedGTO said:

smgee said:

I bought a used pair of rear silencers off Ebay, sliced them open, gutted the insides and turned them into straight-through silencers by welding in a perforated pipe, packing them with sound-absorbent material and welding the cases back together again.

Did you take any photos? I've always wondered what the inside of the stock silencers looks like.

You could cut out the small cylindrical middle silencers for a small but noticeable difference in volume and burble (if it's a facelift CV8). You could also try removing the resonator and replacing it with an h pipe, x pipe or straight pipes. I have thought about this, but am worried that doing so may actually decrease exhaust noise in the cabin, especially windows up, as I suspect (but could be wrong) that it acts like a mini echo chamber under your seat.

I'm surprised that your modifications to the rear boxes didn't have more of an effect. Have you heard the car from outside? Maybe it is a good bit louder. Bear in mind that all that noise is being directed rearwards so you really need it to be significantly louder before you'll notice much difference from the passenger seat. This is one of the frustrating things about exhausts. Passers-by get most of the benefit of your expenditure!

I did just that after a suggestion on the forum, see:

http://www.hsv.org.uk/topic.asp?t=1059960&f=69...

Very worth while, quite a big difference I would say. Several positive comments from jo public.

[Lil'RedGTO]

Yes, having done this i agree it's an improvement. I believe that a system without the middle silencers is basically the stock GTO system in the US. Presumably the extra silencers were added to UK cars for slightly stricter EU drive by noise regs. £100 for an exhaust place to cut them out and replace with straight sections of pipe. Perhaps in combination with the modified back boxes OP you might get the sound and volume you are looking for.

I still sometimes wish my system was a fraction louder though, hence my wondering about going to the next step of replacing the resonator. If i was doing it I'd replace it with an h-pipe which should give a deeper note at idle, but as I said I worry that I might not get much benefit in the driver's seat. What if the resonator has been designed specifically to allow the driver to hear a bit more exhaust noise in the cabin?

Modifying the rear boxes appealed to me as it wouldn't alter the basic layout of the system, but the OP's experience suggests that this may not work as imagined.

Thanks for posting the pics by the way, OP. I can't begin to fathom how they come up with such a crazy scheme of chambers and disconnected pipes.

[granada203028]

I bought the system of eBay for £46. I always thought it must have bean a factory system as it is well made and fitted perfectly. And I still have my old system complete.

Even with the middle boxes 05 CV8s are louder than the stock 4 tail pipe VXR system. Failed the noise test and as a quick bodge Vauxhall had the UK CV8s fitted with the 04 gearbox with taller ratios, so didn't get the improvement the VXR had.

I could see the weakness of the gearing when I bought my car new so very annoyed when I found my car had the wrong gearbox and so had to replace it myself

[MyM8V8]

granada203028 said:

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I could see the weakness of the gearing when I bought my car new so very annoyed when I found my car had the wrong gearbox and so had to replace it myself

If you had ever done Thunder Road you would have praised VX for their foresight in keeping the old box