Many of the top runners at the Pure Stock drags (
www.purestockdrags.com ) use Walker/Dynamax Ultra Flows so I ordered a set of 2 1/2" Ultra Flows to go with my 2 1/2" mandrel bent TTI exhaust system. The Ultra flows perform very similar to the Hooker Max Flows in the chart posted above. This isn't surprising as they share the straight-through design.
The stainless ultraflows are crimped similar to the stock mufflers. They are also available in aluminized versions, but then they use welded construction. You won't fool anybody into thinking the s/s ultraflows are NOS mufflers, but if you turn them so the stamped "dynomax" logo is facing the floorboards, then they look semi-correct.
I'm told they are fairly quiet, but I haven't fired mine up yet. If you want something that looks sorta stock, but performs way better then I would recommend the ultra flows. They are a little pricey, though.
http://www.dynomax.com/products/ultrafloss.htmlDave
