I'm about to fit my T34 .60/.48 with an ERST ehaust housing but I want to know, does anyone actaully have any back to back tests to show the differences between using the Cosworth .48 exhaust housing and downpipe and an ERST .48 housing and downpipe?

I know the Cosworth set up is supposed to be less restrictive etc and worth fitting but just how much better is it?

Jano gave me some good advice about it yesterday, but if we are talking a big imporvmeent I would do the extra work to fit one.