mufflers

Okay as promised here is what the new Dynomax VTs do for you.

My brother-in-law has a 1968 360 Barracuda coupe. It runs 12.40s at 108 or so with full relatively quiet exhaust. It had Magnaflow 18" 2.5" offset in and 2.5" center out mufflers with 2.5" inch shop bent tail pipes.

We first installed the stiff spring Walker Dynomax VT 17956 mufflers. The goal was to kill the drone at 1850 rpm up to about 2350 but still have some tone. Boy do they work for this. No roar or resonation anywhere and that is with the back seat out of the car. He runs headers with 3" front pipes to 2.5" out of a true Dr. Gas X-pipe.

We then swapped on the Dynomax VTs with the light spring. These are 17156s. They indeed have more tone and slightly approach resonation in the lower ranges but really they never got there. You all with 340s know exactly the roar and resonation I am talking about.

The sound levels, measured from 10 feet, look like this.
---------------17156 ------ 17956
Idle, 800 rpm-- 78 dBA------- 75 dBA
2200 rpm------ 83.5 dBA ----- 81 dBA
3500 rpm------ 90.5 dBA ----- 91 dBA

Back pressure wise, it is very hard to measure with the tap we had at the collector outlet. Both fluttered around 80 inches of water at cruise but at WOT only slightly rose from this. Bear in mind this includes tailpipes.

What this tells me is this: Walker did a fabulous job of fixing issues with loud mufflers this time. No resonation and yet a really cool idle sound and snarly WOT sound. They really growl at WOT but an outsider can hardly tell they are 3" mufflers with only about a 8" to 10" long perforated sections internally. In other words, these short mufflers do a hell of a job of muffling at cruise and a really tremendous job of eliminating the resonation/drone/roar that pisses off so many people, me included.

Tom