Right... getting to that stage!

The new plan is to use both the OEM manifolds (1.5 inch pipes to 2.5 inch collector) - a short 2.5 inch link pipe for each (no cat) - and then 2 back boxes.

What considerations should I make in relation to selecting the 2 back boxes?

Is it safe to assume that any box with a 2.5 inch inlet will be a safe enough bet?

I may be wrong but i think r1 can's have 2 1/2ins pipes going in
it may help you

Make sure the back boxes are long enough. I fitted ones about 18" long and the noise measured 109.5dBA thats about 50% above our local track limit. Apparantly the longer the box the more effective it is

Are you sure you will be OK not fitting catalysts? How old is that engine (IIRC Audi V8).

John

In discussion with Merlin, they said it is the width (larger diameter) of the silencer box which reduces noise rather than the length.

quote:

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Originally posted by mr henderson
Are you sure you will be OK not fitting catalysts? How old is that engine (IIRC Audi V8).

John

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Ah! so it's the width that counts.

I always thought the width altered the frequency and the length was the attenuation.

Merlin should Know I wonder what the ratio is? Twice as wide twice the attenuation?

David

Some interesting stuff here

http://auto.howstuffworks.com/muffler1.htm

John

Ta