[Ant]

I am starting to build my sidepipes, and have room for about a 22" long muffler and 10-12" long 3.5" turnout pipe! Have some 3" perforated tube organised, I maybe better to go to a 4.5" diameter sidepipe case for more noise reduction, that leaves 3/4" all round inside for sound proofing material over a 4" muffler with 1/2" room for glasspacking, so I wonder if the extra 1/4' of glasspack will actually make a difference if I went to the larger 4.5" tubing, and I guess the larger the tube the uglier it gets! The benefit maybe in slowing the gas flow down with the larger tubing.

For extra noise reduction, I have seen to good effect 3-4 small perforated tubes same length as the 3" tube, used as a removable baffle, apparently this makes a significant sound reduction, but should allow me to do a small bit of town driving!