I have a single 3inch mandrel bent exhaust feeding off a set of 1 3/4 bore Pacemakers behind a fairly stout 351 in the XD. Muffler is a Genie straight thru type.
The motor is at the rebuilders now getting some more work - stroked offset ground 351 crank, Chev rods, etc - to take it to 377 cubes. Upgrading the cam to a pretty large Ford motorsport solid (not sure exact specs) but it's a 3000-8000 sort of cam.. The 2V heads are getting their 3rd overhaul with some pretty serious porting and all the usual stuff.
Not sure whether the 3inch single system is up to scratch. I was wondering if someone has compared the performance of twin 2inch, twin 2 1/4 or 2 1/2 -vse- 3inch single in a similar combination.ie stroked Cleveland?