I'm looking for a definitive answer as to what is the better exhaust combination for forced induction applications.
When my engine was first converted, I had a newish 2.5" Milltek cat back system. Over the last 2 years, well, fairly quickly, it became apparent that the Milltek centre section had become empty. All the wadding has been burnt away.
I have asked what effect that an empty box will have on power and performance and i've not really had a 100% positive answer. In my way of thinking, with forced induction, you want to get the increased amount of gas out and away with as little restriction as possible.
Gases flowing along the pipe into a 'good' centre section, the noise gets absorbed by the wadding but the gases are still channeled through the centre uninterupted and out the back.
What happens with an empty box scenario? Gases flowing along the pipe into an empty box, nothing to absorb the noise, the gases are now interupted as the gases are swirling around filling the centre box before exiting the box and out of the rear.
What effect is this having on power? Would it be better to remove the empty section and replace with a straight through pipe with no interuption of gases and a slight increase in noise level or would it be better to keep a centre box with a higher grade wadding?
What is better for optimum power gains?