SP back box & Decibel insert

[Luckyone]

As there seemed to be a lot of interest last time I thought this may be of some help to some one…
It has been mentioned on here before & I have posted a link to demon tweaks, but I have just been taking to the people who make the insert www.jetex.co.uk  they are for 3inch pipe only & the SP tails are 88mm almost 3 ½ inch so they WON’T FIT!
The chap said all they do is restrict the flow to increase the back pressure so there’s no guarantees they will work anyway. He said I could try a Stepped sleeve http://www.jetex.co.uk/website/images/u078900box.jpg  to as it would have much the same effect, but it won’t fit in with out some massaging & you’d need to drill a hole in the nice SP tails to hold it.

As we still have some track day silencers for that were for the org system I just went for some double end sleeve that I can weld onto them so they will fit the SP system http://www.jetex.co.uk/website/images/u068900box.jpg 
So we can take them just in case. An alternative would be a pair of these http://www.jetex.co.uk/website/images/u458900box.jpg 
To slip on if you needed them.

The car did struggle passing 98db with a totally standard system on before, I’ve just put the non SP linked de-cats back on after running with the cats for a while – scared the life out of me! One hell of a difference, with the cats its sounds quite refined rather like an Aston Martin when on full chat, with the de-cats it’s very raucous - fighter plane like when you boot it, but still very civilised below 2.5k which is the whole point of it.
How SP get it to pass 98 regs with de-cats is beyond me, ours tested to 105db (this was put down to the non SP linked de-cats) although I think ours could be louder than others as the guys at Mole Valley (TVR main dealers when there were going) all though it was running sports pipes the first time we pulled up there.

[touching cloth]

That's a shame, was about to order some of those inserts - hadn't even measured up just thought the exits were 3" for some reason.

[Luckyone]

touching cloth said:

That's a shame, was about to order some of those inserts - hadn't even measured up just thought the exits were 3" for some reason.

Me too - hence the post

Hope some of the other options are of use to you.

[Nickccc]

Simple, we all chip in have some made maybe a batch of 10-20 for starters,
who's up for it?

[touching cloth]

Yup

[Nickccc]

Sounds like a plan then, I guess it makes sense to do this inconjunction with SP and their exhaust people, we approach Mat or Phill and ask them if it is possible, I am going up there Friday so will run it by Mat, no doubt Phill will see this and maybe talk to the exhaust people.

Nick.

[Byker28i]

This sounds like a good plan. More and more trackdays are starting to put a lower noise limit in of 100db or 102db and starting to raise the revs to 4.5k. The ACT trackday silencers are great at reducing the noise on standard systems with 2.5" pipes, but can leave scratches on the exterior of the tailpipes. This is something I'd like to avoid with the nicely polished SP system.

[Luckyone]

Nickccc said:

Sounds like a plan then, I guess it makes sense to do this inconjunction with SP and their exhaust people, we approach Mat or Phill and ask them if it is possible, I am going up there Friday so will run it by Mat, no doubt Phill will see this and maybe talk to the exhaust people.

Nick.

It does sound like a good plan! Nick if you are talking to them, it would be interesting to get there take on simply increasing back pressure to reduce the noise, rather than adding extra silencing.

Byker28i said:

The ACT trackday silencers are great at reducing the noise on standard systems with 2.5" pipes, but can leave scratches on the exterior of the tailpipes. This is something I'd like to avoid with the nicely polished SP system.

Yes this is a problem, also they add a lot of extra weight to the end of the exhaust, I'd guess putting a much larger strain on the rubbers & the whole system when on track.
Something internal would be a much better option.

[Nefarious]

Byker28i said:

The ACT trackday silencers are great at reducing the noise on standard systems with 2.5" pipes, but can leave scratches on the exterior of the tailpipes. This is something I'd like to avoid with the nicely polished SP system.

Yes this is a problem, also they add a lot of extra weight to the end of the exhaust, I'd guess putting a much larger strain on the rubbers & the whole system when on track.
Something internal would be a much better option.

I've got ACT trackday jobbies that I'm planning to take to the ring with me. Never used them so far, but my plan is to weld an L-shaped bit of tube on each, thread a loop of cable between them and support the whole thing with a bungie looped around the boot catch and shut in the boot door.

[Nickccc]

it will be an insert type, no heavy slipon's. Probably a perforated series of conical discs, think mute for a trumpet shape, may need a split pin so as not to blow out. I don't mind using my back box as the tester, i'll keep everyone posted.

[Byker28i]

Whilst the ACT silencers work great at reducing the noise level, I was never happy with the additional weight on the end of my sports boxes. It used to make the tailpipes sag slightly and I replaced the rear rubbers once which may or not have been a factor. One of the reasons I went for the full SP system.