So... I'm building a 300... Mild cam, 4bbl, and long-tube hookers..
All emissions removed. Planning to run dual exhaust, and I'm curious what diameter pipe i should be looking at, and whether or not to put some kind of equalizer pipe in there

 

2" is more than adequate. An X pipe or H pipe can be used but I think there is little benefit if any performance wise on an I6 engine. The firing order does not create problematic exhaust pulsing like that of a V8.

 

I agree with what Harte3 said. Dual 2" is plenty big enough on a mild 300.

 

I just finished the exhaust on my '86. Used tube headers with 2.5" collectors. Necked down to 2.25" pipes, universal cats (2.25") from Ebay, 2.25" glasspack mufflers from Jegs (Red Hots or something. about 18" of muffler body). Dumped out in front of the right rear tire. No cross over pipe. True duals. System sounds good. Quiet at idle, but makes some noise as the revs increase. It's got some pop and cackle on decel which I think is cool. Seems to let the engine breather better than the stock system. Put a Offy DP and Holley 600cfm on at the same time. Can't really say if the low end torque has been impacted or not. Mostly it's a DD street truck. I pull a small utility trailer with two or three motorcycles on it, but nothing gianormous.

For the cost I'm happy with it.

Just an FYI, but the glasspacks have a "quiet" direction and a "less quiet" direction. I had mine installed in the "quiet" direction. Has to do with the direction of the inner baffles.

Tracy