[scottj]

DaveR,


Yes, yes, 91. Correction: not a 1/4", closer to .190

You can't believe it fits can you?

I cut 13 slots around the circumference by 7 slots lengthwise over 24". I wrapped the core with a fine stainless steel wool from a 12" wide roll and wrapped that with wire to hold it tight. Then I took a tapered style piston ring compressor for a 4" bore and turned a step in it on the lathe so it could be tightened securely on the end of the 4" pipe. Then the core could be shoved in without snagging on the outer pipe.

If you don't mind the look of a 5" pipe they could be allot quieter and still perform like an open pipe. Although a 3-1/2" core will never be "quiet".