1.875, 2, 2.125", any one will do for taking the sharpness out, but it must go first, then the 50's or 40's. If you do it the other way, it'll drone. TMust people think that glasspacks should go on the back, with 3 element front mufflers. This is wrong!
You can have, say, a Clifford of FSSP dual out header, then two 2.125" short glass packs, but then you must use two mufflers which flow over 300 cfm at 25" of water. Most of the old Cyclone Turbo mufflers in the 2.125" range could flow 350 cfm without passing lots of noise on.
Look at all modern exhasts from Japanese Nissans, and see how they did it. Inital sharpness is taken out by resonators of catalysts, then the multi box tail pipes do the rest.
Try glass packs and down turned exhasts, but I think it will be too noisy. The sound waves form a reflecting pressure wave, which travels back up the pipes to the header, creating a resounding noise. In the days of 180 hp heavy full chasiss Mercury lead sleads, the lowness and the exhast megaphones made it sweet. I've heard some of these old beasts, and they are great. These days, though, it makes a unibody Ford sound like a droning Lycoming plane.
I'd look at the old V8 muffler system, and try to repicate it with two resonators, and then two hi flow 3 element mufflers.
If I'm wrong about this, I'll take the heat. I'm building one for my Falcon shortly, and I can't afford to mess it up.
My sources are primarily:-
David Vizards Mini and A-series (1980's)
David Vizards and SOHC Ford, (1980's)
New Zealander Rob McGavin's Modifying Your Mini for Modern Motoring Conditions. (mid 1990's)
a series of advertorials by the Lukey Muffler company in Street Machine (2001 to 2003).
20 years of Aussie Street Machine Technical articles.
My mate on the paving crew used to work at Midas, He did my Cortina before I owned it in 1996, and later gave me some great advice too. He has been instremental in making me look at slipper joints and flanged exhast systems, rather than just buying stuff that doesn't work.
