LeBlanc
Look also at the new Dynomax VTs. You could run the 17956 and have a sweet sound, no drone, and plenty of noise at WOT. They really are pretty darn slick. We have three sets we are playing with right now. And, there is rebate on them too so for $75 you get state-of-the-art technology, great sound, no drone, and all stainless steel body and tubes.
We just put a set of 17956's on a 12 second 68 360 barracuda. I have two more with the weaker spring (17156) coming this week and we will do a comparison between them to see what affect the spring rate has on back pressure and sound level at various RPMs. It is weird that such a short muffler, with a 3" core with minimal packing, has such little resonation and roar inside during normal driving situations.
I have had 340s since 1978 and they are very tough to keep from resonating from 1800 to 2300 RPM. This muffler seams to prevent that roar very nicely.
As soon as we get the whole system sealed and leak free, I will try to get some very good sound recordings to share along with the data we plan to collect. Should get measurements later this week.
Tom