undy,
FYI: This topic has been reviewed over and over at length here on CC over the last 2-3 years if you search around. If you have a healthy cam/compression and heads on that Pond motor, some 2-15/16 peforated core baffles,
non-leuvered, 20.5 long canisters, with chambered entry/exit will do the trick and it will ROOOOOAAAAAAARRRRRRR!
To me, all these other turbo baffles, directional louvered units, cones, and every other flim-flam gadget out here inside the sidepipes are just different variations of restriction if you ask me and some are actually louder than a well designed chambered glasspack exhaust setup. I pretty much concluded last year that one could achieve the same results with a $8K 390 FE motor and improved sidepipes as compared to a $20K FE motor with factory sidepipes that come on many of these replicas/kits. This seems to be a repeated oversite with many of these high $$$ cars out there. A few Cobra folks in my neck of the woods with small blocks have picked up 40-60hp rwhp on the dyno with improved sidepipes and others have claimed more but I did not see the before/after dyno sheets myself. My stock mufflers are sitting out at the scrap metal yard or melted down somewhere by now
Good Luck.