I have a 2.5"  true dual exhaust on my car that i just sqwashed when my driveshaft bailed at mach 3. i have Thrush Turbo mufflers on it, the short ones (19" i think). now its quiet enough for me, but the old man (ya i still live at home) is worried about pissin off the nieghbors (i don't want to either). So i noticed that they make a 22"ish muffler. Would that be quieter than the short ones?

Thanks  

Yes those longer mufflers will knock db's and using 2-1/4 tailpipes would also drop db's.   WIEDER  

you might check out mufflers for a 92 cad fleetwood rear wheel drive with a 305 or 350 ,... available at most parts stores... they use a 2-1/2 inlet and outlet..  and are single on the cad app... so duals should quiet it down significantly.. and still let the power through...  the 93 cad rwd fleetwoods used the same mufflers but in stainless..

several of my friends have done it... and love them...  

flowmaster 50 or 70's  

I have the longer ones, summit versions, on my Caprice with a 454. Even with 2 1/2 exhaust, they are pretty quiet, but I don't have headers.

Here's of vid of it running.
 

"Mach 3?"   I'll bet it was the shockwaves that got to that broken U-Joint and not lack of lubrication or one-too-many "neutral drops."

Forget the "turbo muffler" and go straight for the TURBO (they make great mufflers as a side effect to producing boost). . . .   Just tell "pa" that it's a new "high tech" "active muffler for better gas mileage" . . . "those little blades beat down the sound waves".


But if you don't want to dump your current mufflers (assuming they're not "sqwashed"), you could take a page from Detroit and add some straight-through resonators to the end of the pipes  (I like this option better than going to smaller 2 1/4 inch pipes -- which I'd never, ever, ever run for any reason other than lack of clearance for larger pipes or lack of funds. You never want to do anything that adds backpressure, such as an undersized tailpipe.) If you flange the resonators, you can make them removable.

Flowmasters are too loud and too expensive, but they're sure popular (with everyone but Turbo Ted,  some cops, and a lot of overly-sensitive wives and parents).

I like the Flowtech Warlock because it has a bypass plate that can be removed once you're out of your Dad's "sonic" hearing range.  But you might still need resonators with this one.

Note that turn-down tips will sound quieter at part throttle that straight tips.

If you're looking for a no-coin solution, you could make a removable tail-pipe plug/baffle with a smaller exit hole, similar to a motorcycle baffle (not a good highway solution because of backpressure), but it will get you quietly out of the neighborhood. I suspect if you could find a small truck rain cap (they're usually a lot larger than 2.5, though) and drill a one-inch hole in it, you could have a tough "flip-down" plug that would muzzle the sound when you need quiet.  


One final tip: Idle around your neighborhood like grandma and don't rev or "rag on it" until you're well clear of the neighbors.  I've gotten by virtually unmuffled at times by using this low-profile strategy.  

On the other hand, if you're shooting "sydeshows" for Youtube in your 'hood, or "baking cookies", or poppin' yer jy meats (we used to call it "peeling out" back in the leaded gas days),  or pulling five-grand holeshots at midnight,  no muffler ever invented will appease the neighbors.

Something to think about.  

No I just do Burnouts or peeling out, NEVER do neutral drops. and I know how difficult it is to believe but Mach 3 was 143mph, 5300rpm lock up in third gear with 30.5 tires and 3.42's in the rear end. And the driveshaft split in the middle (never found that 2 foot section) I have the front 19" and the rear 19" with only 1 cracked u-joint!

But as for the Mufflers I had my buddy redo from the headers to infront of the rear axle. Also had him put on dumps by the headers. I stuck with the short mufflers. They're not to loud and after talking to my 84 year old neighbor he doesn't seem to mind the noise and is appreciative of my hobby.

What I really like about the Thrush mufflers is that they dont have that god awful drone that Flowmasters have and they cost $22 not $120