Sonic Turbo Mufflers

[The Bushwacker]

I had 'em on a couple of cars, in the 80's. They were the best. The sound may be a little too quiet for guys that like it so you can't hear the stereo at full blast.
The Sonics had a nice sound that I really liked. But I didn't pick them for the sound. I wanted performance.
I read a heck of an article (Hot Rod, I think) where they tested all the turbo mufflers on one engine (Chevy), sitting on a dyno. In fact, they also threw in a couple glass packs of the day. The article, and the results were amazing. You think a muffler is a just a muffler, right? Wrong.
From running stock OEM exhaust, the glass packs actually reduced horsepower by like 8 hp. Pay attention Thrush fans. Glass packs create turbulence!! All the turbo mufflers tested ran a wide range of increased horsepower. A couple were around 10hp increase. Some were like 20hp. The Sonic Turbos increased the horsepower like 30hp (I forget the exact number now).
My car at the time was a pretty much bone stock, El Camino, 350 ci., with the 500 cfm Rochester. I had tweaked and tuned the carb till it was perfect. I did put in a roller timing chain when the old one got so loose it wore a hole in the cover! LMAO I just kept playing with the car. I'd gain a second here and there. Different rear springs made a difference. '73 was the height of gas milage paranoia, and all the Chevelles, Impalas, etc. came with rearends around 2.8 (I forget exactly). I put in a rearend from a Monte Carlo. The Monte was the only Chevy in '73 that got a lower rear end. It was 3:08, I remember. That dropped my 0-60 by a full second.
The last thing I did was add dual exhaust with Sonic Turbos. We're talking about just the right sized pipes, an H pipe, etc. Still stock cast iron exhaust. I gained another full second, 0-60.
BTW, you guys that think bigger is better, I was running 1 3/4 inch to the mufflers, 1 1/2 inch to the back bumper. The trick is, getting the H pipe just the right distance from the engine, and putting the mufflers at just the right spot.
When I was done, that tired old, bone stock 350, with 100,000 miles on it, could do 0-60 in 6.9 seconds. Remember, cars like a GTO, back in the 60's was bragging about 7 seconds!
You will call me a liar, but I swear it's all true.
One of the best carbs for short run, street racing, was that Rochester 500 cfm 2 barrel. And those Sonics were the best! I doubt that FloMaster can make claims of 30+ hp.