The Magnaflows are a lower priced knockoff of the Ultra Flows, but I think the Dynomax are better built. I've heard of quite a few people running the Magnaflows where the outer skin of the mufflers starts splitting & cracking, plus lots of people complain about the Magnaflows having a wicked drone in the 1800-2300 RPM range. Flowmasters are NOT what you want to run if you want a really free-flowing muffler.

Besides the mufflers I make, I do like the Stainless Ultra Flows. I'll be running a set of prototype stainless Super Turbos we built while I worked for Dynomax 11 years ago. These are reverse flow to go on my AAR. We flow tested an NOS muffler I have for the AAR-T/A & it tested at 175 sCFM. The ones we built for my AAR flow 375 sCFM. I can't wait to hear them!