Very old thread but some of you guys must have different definitions of "quiet" or have much worse hearing than me
I had a ~480-500 hp 383 at 11 to 1, street pump gas motor. 1 3/4 long tubes into 3" collectors into a Y pipe that was 4" outlet all the way back to the axle then splitting into dual 3" to the bumper to give dual tips. Had a Dynatech Split flow in there before the axle split, in the intermediate pipe section they call it.
DEFINATELY NOT QUIET like some say in here.
Not any quieter than open Y pipe.
Replaced with a 16" Dynomax Ultraflo round. 6" round case, 4" inlet/outlet. Alot quieter than the other muffler and open pipe but still pretty loud. WOT was deafening. Could hear that car miles away. Sounded awesome tho.
My turbo motor... 9 to 1 comp 401" EFI motor. old combo had small heads, smaller Jones hyd roller, twin 60mm then 70mm turbos with same hotside, and first had the same single 4" as the 383 car did with the ultraflo. It was pretty quiet. Couldnt hear it down the track like the 383 when you stood in the stands.
Switched to dual 3" with bullets....still quiet on that car. SO thats good for a street car.
New turbo combo is larger heads and bigger cam, new hotside with same 70mm turbos. Its once again very loud not sure why. I guess heads/cam moving lots more air. Bullets were too loud. So now I have the 12" long case/ 16" overall length dynomax ultraflo stainless mufflers with 6" round case. Look like little Fart cans but they did a good job quieting it down but STILL much louder than the old setup. So I'm putting the bullets on the car behind the ultraflos.
If you guys have 800 hp all motor cars and cant hear them, then something is wrong with you