PVFCpug 6 Posted December 19, 2006 Hi recently had quite alot of work done on 205 MI by DES in Walsall (Top Guy) and he fitted a new SS group N exhaust. First track day with it at Oulton and it measured 104DB. Problem is I would like to use the car on as many different tracks as possible but obviously the sound is way over the top for some tracks. My next closest after Oulton is Donny and they are very strict. Any ideas on sound reduction and is it neccessarily the exhaust I am running twin 45's and wondered if it could be a combination of exhaust, induction causing such a loud reading. I have heard mentioned an insert for the exhaust pipe, does anyone else know of any such item. Or do I bite the bullet and get an mid section silencer added? Idea's gratefully accepted Share this post Link to post Share on other sites
Richie-Van-GTi 71 2 Cars Posted December 19, 2006 you can buy an insert yes, have a look at www.carbuildersolutions.co.uk they do one in their catalogue. Share this post Link to post Share on other sites
jackherer 543 Posted December 19, 2006 Group N noise limits are apparently either 96dB or 98dB ±2dB @ 3800rpm so thats a bit dissappointing as I planned on buying one of those 'Group N' exhausts but theres no point if I couldn't use it on track. Share this post Link to post Share on other sites
boombang 2 Posted December 19, 2006 grp N is 95db +/- 1 db but what you have to bear in mind is that is on a perfect tune grp N spec engine! If you put a lot more through it then noise will increase, however more critically a engine slightly out of tune, or one with poor cam timing will be a damn site noisier! Share this post Link to post Share on other sites
smckeown 1 Posted December 19, 2006 Wel lto be fair they are slightly larger diameter than the group N, so they will be slightly more noisy. But I've talked with Des in detail about exhausts and noise, and those figures do look high. I'd recommend getting in touch with them, they are comitted to customer satisfaction and always offer excellent advice. As alex says it 'could' still be a setup issue Sean Share this post Link to post Share on other sites
jackherer 543 Posted December 20, 2006 seems to be a lot of different figures for the Group N limit, I had heard 98 so I googled it and found both 96 and 98 listed in different places so I suspect its maybe changed over the years or something... Share this post Link to post Share on other sites
PVFCpug 6 Posted December 20, 2006 Wel lto be fair they are slightly larger diameter than the group N, so they will be slightly more noisy. But I've talked with Des in detail about exhausts and noise, and those figures do look high. I'd recommend getting in touch with them, they are comitted to customer satisfaction and always offer excellent advice. As alex says it 'could' still be a setup issue Sean It was DES that did all the set-up using Hi Tech RR, was running a very poor 165BHp until they git there hands on it now reading approx 200 (211 on the RR with 5% error). I do appreciate the Group N is designed around a Group N engine of which mine certainly is not. The Mi 16 I have in runs twin 45's and ported head so that also will add to the Db reading. My gut reaction is to see if DES can put a repackable centre box in which should not be too restrictive but quieten it down a bit. Very difficult to judge and you could spend a fortune trying to reduce the noise only to find a small reduction, Neal has mentioned a straponectomy exhaust attachment. The 104 was a static reading BTW does it get noisier actually taking a track reading if so then I've blown it for Donny. Maybe just have to stick to Oulton, Anglesea and other noisier venues. And of course keep upsetting the neighbours........ Share this post Link to post Share on other sites
TT205 42 Posted December 20, 2006 What rev's did you measure it at? If your red line in 6200 you test at ~4200 supposed to be 2/3 or 3/4 max rev's - can't remember which And 6200 is your max revs isn't it Share this post Link to post Share on other sites
smckeown 1 Posted December 20, 2006 it's not alwats at 3/4 rev limit, at goodwood i got tested at 3/4 the start of my red line. I think they were just beong helpful, as I have easily failed it 2 times previously on 3/4 rev limit Share this post Link to post Share on other sites
Dj_mini 7 Posted December 20, 2006 Did you not go for the twin box option on the des system? Share this post Link to post Share on other sites
PVFCpug 6 Posted December 20, 2006 Did you not go for the twin box option on the des system? Nope fraid not, single back box on it. Share this post Link to post Share on other sites
