Ok Johnny , the tail pipes' will swivel in every direction so with that in mind....rear flange bolt to rear weld...10 1/2 to 11 1/4 " . Rear flange bolt to tip 19 1/2 to 20 1/2 " . Both measurements you could probably stretch a bit more in either direction . Both measurements taken from center of last mounting bolt hole at transom end of head . Now , if you look in the pictures you see a mounting plate that bolts to the head first , then the header mounts to that . Exhaust holes in the mounting flange are 1 1/2 " in the headers they are 1 7/8 " I .D . You can also get a little movement out of the mounting flange . Tailpipes' are 4 1/2 " diameter . These were on an OMC setup so should be the same as your Volvo .

cmi headers
 

Have you sold the headers yet or ready too? If you want to sell them give me a call at 315 623 9583. Thanks jim

I don't think you will see any advantage using those exhaust systems at that HP level. I'm spinning a 377 SBC to 5600 so far with GLMs and Ryan has spun closer to 6000 rpm with GLMs if my memory serves me correctly. So I don't think exhaust is the limiting factor at the 400 hp level in a SBC. If you want to wind them up to 7000 rpm (:eekdrop:) you may want to invest in the CMIs.

From my perspective I would much rather spend the $3000 in engine internals rather than JUST on a set of pipes.

Having said that CMI's do look good.