I have a Magnaflow 3" exhaust system on my 71 Challenger. I have a 505 stroker in it and I must say these mufflers are so loud that it doesn't seem they are even on it. I was thinking of going with the Borla mufflers but wanted to see if anyone has these on their car and if they like them. Thanks

No exp with Borla but what about some vacuum or electric cutouts right at the collector along with restricted (quiet) muffs (maybe 2 per side? Quiet most of the time (keeps cops/neighbors happy & you happy) & full power (& noise) only for the 10 seconds stretch that it is needed. Helps with the shock/stealth factor! Otherwise with a good (more restricted) muff choice I would suggest an X pipe system with in addition glasspacks alongside the leaf spring (Cherrybombs I used have outward punched louvers & no neckdown where the end nipples are welded to the case=least restriction) and lookup Helmholtz (sp) resonators in exhaust science something about welding in some some 1 foot or so sideways horizontle pipes in the bend over the axles & capped on the ends, something about it cancelling sound waves as tehy bounce back & reportedly it works. Loud pipes is high school stuff & I prefer to overwhelm em when I drop the hammer! Holler how it turns out as I wanna build a 543 with a 'source 2k RB stroker kit when I hit the lottery. I have a good block so I'm on my way. EDIT good info on youtube if you have the time

i run stock 'hemi' mufflers on my 440 road runner and am very pleased with the sound. quietish idle but a monster when i get on it. are they restrictive, probably but for the once in a blue moon that i wish they weren't the trade off isn't really worth it for me. i have no drone and no complaining neighbors. well except for my barking Shepard Sir Yaps-Alot!

I prefer the dynomax ultra flows, not a fan of magnaflow or borla.

However a few questions first. Where do your tips dump? Straight out the back, turn downs or axle dumps?

Also, which ever muffler you decide, go with the longest muffler you can fit. Don't cheap out and buy the shortest one in the product line you fancy. Longer muffler = more noise reduction.

I have them dump out at the stock location in the back. The mufflers that came with the system and the Borla mufflers I'm looking at are 14" long. I believe that's the longest I can fit under the car.

are the current Magnaflows mounted under the rear seat in the stock location or behind the rear axle where the stock resonators go ? If under the rear seat you might want to move them back to where the resonators go
I had my early 14x7x3.0 Magnaflow crimped muffs. mounted back there to start with and they where halfway decent sounding at part throttle cruise and got a lot louder at WOT
That set up, 3.0 pipes from the A body Hooker fender well 2.0 inch primary pipes with 3.5 inch collectors back to the muffs mounted at the rear bumper only slow my car (1971 BB powered Duster down .02 ET and .2 MPH in the 1/8 mile, 6.98 ET to 7.0 ET and from 95.6 MPH to 95.8 MPH by removing them
My old 440 powered 1969 Dart GTS slowed down .8 ET and 8 MPH in the 1/4 mile with a 2.5 inch system from the same collectors into a set of the older 2.5 inlet and outlet Turbo muffs and then into a set of 2.5 inch side exit pipes in front of the rear tires
Let us know what you decide and the results please

Another vote for Dynomax UltraFlows.

There is no way that they would fit where the resonators go. Its next to the fuel tank and the muffler being a oval shape would have to sit at a angle which most of it would be hanging down below the pan. The only place they fit on a E Body is under the back seat. Beleive me I did try to put the all the way in the back.

one picture is sideways the other upside down

It's a combination of the pipe size and the straight thru muffler. Do you have an H or an X pipe ?

Get a bullet type resonator and put them next to the tank and see if that tones it down some.

Classic chambered sold/made by the board member in Michigan ...

Look at the Jones brand of mufflers on Summit's website.

OK - you have room for some 3" core & 4" OD body resonators back next to the gas tank. 18" long bodies. Give me a call & I'll make you a set.

-Eric

www.classicchambered.com

Do I put these on in place of or with the mufflers?

you install these alongside the springs in addition to your regular muffs up front. I would use some cheap parts house "cherry bombs". the louvers are punched outward and the end nipples do not neck down where they are welded to the main case (both for no restriction). if you can get these in 3" I would. I have a pair on my 85 Ramcharger (by themselves) & they do muffle adequately & they will help you for cheap. (maybe even (2) per side if you have the room). EDIT I just called O'reillys & they have em in 16 & 28" lengths (3").

Guys, if the OP thinks his current Magnaflows are too loud, he's not gonna be happy w/ Dynomax Ultraflows either. They're so similar it's not worth making the swap.

If you want it quieter, then go w/ something like a Dynomax Super Turbo. Much quieter than the straight through style mufflers, but still sounds real good. Just be prepared for some loss of power.

I want my exhaust loud on my car so people will stop texting and avoid running into me.

This past weekend I used a sawzall to remove a set of Dynomax 2ft-ers off my car...no clue what type, but they were long and super quiet. Replaced with a set of Magnaflow's and I was actually pretty shocked how quiet they were at idle, but plenty pleased every where else. If they become annoying on the highway, I may add a set of glasspacks or resonators after the axle hump to calm them down a bit.