[AMCJavelin74]

One thing that wasn't mentioned are turns and bends...

I know a lot of guys like 'blackpipe' but I really think using it impedes exhaust flow (as it's OD is the same as 'normal exhaust pipe' but the ID is smaller. This creates a hard angle for the exhaust gases to manuver around as it narrows down- even if you use a straight section.

......s are to take up space as some formatting keeps my diagram from turning out how I'd like.

------------
................L___________
exh. port........blackpipe ID
................____________
................I
------------


While the above is up to debate as to wether or not if would affect engine efficency or power significantly, the elbows are what scare me.

Look at the inside of a blackpipe elbow at the hardware store, then find a nice angle or pressure bend pipe. Which would exhaust gasses flow easier through? As for 'standard exhaust pipe' bends, at the worst is crush bent. The inner radius of this bend is all crinkly. Normally found in parts store bins. Then they have pressure bent pipes, which the inner radius is smooth, but a smaller diameter than the straight sections of pipe. I think this is an ideal 'bang for buck' bend. And of course we round it off with mandrel bends, which keeps a diamter consistent through the bend. I'd go with this (a little pricier) if you have a competition engine.

Just my two cents.