I had my exhaust noise level measured today at procomp. It read 107.9dB at 1/2 metre at 8900 RPM which is 3/4 of max RPM. For many trackdays it needs to be 105dB or preferably lower for a bit of leeway.

The chaps said I'd need something a lot bigger than the MNR stainless straight through can that I have or perhaps something "chambered".

What is the best way forward? Can anyone suggest a good (read cheap and not power losing) way to shed a few decibels?

what about a normal R1 can?

Are R1 cans any good? I guess they'll work with an R1 but are they going to be quiet enough? Will I lose much power from swapping to one? Will I need to rejet my eninge again?

My mate has a Zcars mini with the standard supplied can, it was I think 120 db on idle! something ridiculous like that.

Put a standard R1 can on, noise tested at Castle Combe 102.7db at three quarter max revs, made no difference to the performance in fact he thought it made it rev even better

In an effort to quieten the induction roar down inside the car, he also tried a standard airbox, this completely stifled the performance so off it came and in with the ear plugs

Cheers
David

I have a RAW/MK standard can, a Yoshi bike can and will have a Supertrap soon and will be testing them all in a couple of months if you can wait for the verdict!

Pat...

The only power I ever gained with a "loud" read open small race can was very high up the rev range, there is/was a cost too pay though, huge loss of power down the rev range. If you get the noise down by fitting a standard can (there not that restrictive you can see thru them if you hold them up too a light) you will also have a much more driver friendly car and not notice the upper end handful of missing horses.
How many miles you done in the car ? I love BEC's and wouldn't consider anything else in a kit but even I got fed up of the noise from a race can.

I've done about a thousand miles since I got number plates at new year.

Marc at MNR insists that the can is much quieter than 108 dB and says the noise must be a mixture of induction and other rattles / panel resonance. he suggested putting chassis foam strips along all the edges where the bonnet meets the scuttle / chassis / nose cone. We'll see how much difference that makes.

Surely there must be loads of R1 engined cars that have got the noise down to trackday levels.

Mine's a stock carbon R1 can on an 03 R1 with sausage filter, and its certainly quieter than my old blade which was measured at around 103db when tested at Goodwood using an ST repackable can.

Laser by Jama can with a Specific Db killer is a great can for noise reduction and a lovely sound without the Db killer fitted...

Real deep tone