JustCallMeMac

Hi,

I'm going to need an exhaust bung / baffle for my Magnex as I don't think it'll make the 105db noise restriction for the track day I'm going on, in a couple of weeks.

However, when measuring the diameter of the tail pipe, to ascertain what bung size I need to order, do I take in to account the internal or external measurements. The former is 3.5", the latter is 4" I presume it'll be the internals, but I want to be 100%.

I'm thinking of ordering one of these, unless anyone has any other recommendations.

http://cgi.ebay.co.uk/5-Removable-Ex...item4aa4f1916e

Also, does fitting a bung compromise performance in any way?

Thanks

53

iTrader: (41)

Your better off getting a standard STi Backbox for Trackdays and sexing it up a bit if you wish, I did

On a track day bungs are okish on untuned cars, BUT, on yours they will create potentially damaging back pressure which amongst other things will contribute to a very very hot turbo !

JustCallMeMac

Once again, that's good advice Stu.....I did wonder.

OK.....so a replacement back box it is then and I'll need to sort something out fast.

Any recommendations that will meet track regulations?

Cheers

Steve

53

iTrader: (41)

STi back boxes range from free to about £30 I am running 335bhp/375ftlbs with one and it's great

This is mine on the rolling road. Measure 98db at brands but I think the Marshall was pissed or mistaken, I think he meant 89db lol

http://www.youtube.com/watch?v=kOefkDiJePg

JustCallMeMac

I need some more advice if poss.

According to the guy I bought the car fromm almost a year ago, the exhaust is fitted with a decat downpipe and is 3" from the turbo.

It's also been mapped rather well by a certain Mr Bob Rawle and output is estimated at 370 / 400.

Firstly then, will fitting a standard STI backbox be straightforward, considering the aftermarket work which has already been done?

Secondly, will performance be affected / compromised because the re-map was carried out with the current Magnex system?

What I'd ideally like is something that can be easilly swapped over which keeps me below 100db but won't impact on the current performance!

HELP!!

53

iTrader: (41)

is the centre pipe 3" bore as well as the downpipe ?

Quietest 3" system would be the Revolution one from choice. My friend has one on his classic which are normally noisier than the newages and it registered 89db

You buy this as a cat back but it's similar money to a fully branded Jap backbox so all good

JustCallMeMac

I'm not sure if it's 3" from the downpipe mate.

Will try and find out tomorrow so that I can sort something out.

Cheers