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3inch header to 2.25 exhaust to 2.5 inch muffler?

euroz06

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Hi All,

I have a 68 charger with 383. The car was restored about 10 years ago, but im not sure whats inside the engine (likely stokish cam / 650 carb). I've had doug's 3 inch headers installed a while back, the rest of the exhaust is 2.25 inches (stock) with an h-pipe. I also and electrical cutouts in the first part of the exhaust before the h-pipe. I sort of love/hate my cut outs, at idle they sound dope, at full throttle they sound insane with awesome pops on decell, but in the middle - just driving with them open, they sound like a busted muffler. With cut outs closed, the car is very quiet, like too quiet for my taste to be honest (in the past I had a 73 charger with a mildly built 440 and supertrapp exhaust, that sounded dope, but i don't want it that loud tbh).

On my recent shop visit, i noticed that my mufflers have started to rust out and developed some holes, so its time to replace them. I think i like the magnaflow exhaust, so I have two options.
1. on their website I see an option to buy a headerback 2.5inch exhaust for about $1,000k (would need to be welded/installed, so another $500-600 or so), then I'd probably want to install the cutouts again, so that would add another $500 for the kit and welding.
2. I also see that I can buy just the mufflers, but those are 2.5inch (vs 2.25 that I have on there now), but it would only cost me a total of about $500 to install (about $250 for welding, and $250 for just the mufflers).

So naturally, ideally, I should do option 1, but it would be about $2k. - would i get more hp/tq that I would feel out of this set up? Would sound be noticably better with this option? more importantly, if i do upgrade to 2.5 inch cut outs, would they sound better and should i install them after h-pipe/xpipe for a better sound (currently, they are installed after header before hpipe)?

With option 2, would it problematic that I have 3inch header, then 2.25 exhaust, then 2.5 inch muffler, then back to 2.25 pipes? would that like mess up exhaust flow/back pressure issues etc? Would the car sound much better than it does now, or I won't notice?
IMG_6813.JPG

The car is a miami street cruiser, to be taken out with the spousal unit (as required on occasion). So i don't want it super loud all the time (cut outs for that), but would like it better sounding than currently is.

In this vid you can hear the exhaust, at 3min mark I open the cut outs
 
Do what you can afford.
It should be fine with 2.25 pipes and 2.5 mufflers. Not ideal of course, but should work okay.
As an alternative, if you have skills, you could probably get a header back system from jegs or Summit, (house brand) with mufflers, for well under $500 and install yourself, or have it installed.
(And just a personal opinion: mild cam, almost stock engines sound like s#$t uncorked).
 
As for sound, there are basically three types of mufflers: triple pass, (turbos or hemi mufflers) chambered (flowmasters, hooker aeros) and straight thru (magna flow, dynomax ultra flo,, glasspacks)
Pick out the sound you like, and then the size you want.
Shorter, smaller, = louder
Bigger, longer, = quieter.
 
But a couple $20 glass packs and get the sound your car would have had back in the day

I hate those tinny, overpriced chambered mufflers.
 
Take it to a competent performance muffler shop. Headers to 2.5" all the way back.
 
But a couple $20 glass packs and get the sound your car would have had back in the day

I hate those tinny, overpriced chambered mufflers.
Lots of people don't like the "Flowmaster sound" I do like it, but.... if you want a similar , but louder , sound like it would have had, something similar to a hemi muffler, I would expect a 2 1/2 turbo to sound almost the same, but louder.
@euroz06 , what mufflers are on it now?
 
at full throttle they sound insane with awesome pops on decell
I can't understand why people find that backfiring on deceleration to be a pleasant sound. Muscle-cars shouldn't sound like you have a kettle of Orville Redenbacher popcorn sounding through a bullhorn.
 
Lots of people don't like the "Flowmaster sound" I do like it, but.... if you want a similar , but louder , sound like it would have had, something similar to a hemi muffler, I would expect a 2 1/2 turbo to sound almost the same, but louder.
@euroz06 , what mufflers are on it now?
im actually not sure, i would assume something stock'ish (there is no fancy lettering on it or anything), as during the restoration it was restored to mostly stock speck.

Its my understanding that old mopar sound is sort of unique, id like to enhance that sound. Is 1 1/2 turbo a dynomax exhaust?
 
Dynomax Super Turbo is quieter performance option. Search YouTube for the different muffler sounds to see what you like.
 
After a ton of research I've purchased 2.5" Dynomax Ultraflo Stainless Steel mufflers for my 70 Roadrunner. I bought the longer ones that will fit perfectly with TTI's header back H pipe system (Dynomax Part number: 17289, I believe). Right now Amazon has the best price by far on these right now which is why I went ahead and purchased them even though I'm a year or so out from doing the exhaust. Look up TTI they have a great reputation and are less than what you're quoting.
 
Why not buy 2.25” mufflers?
 
I can't understand why people find that backfiring on deceleration to be a pleasant sound. Muscle-cars shouldn't sound like you have a kettle of Orville Redenbacher popcorn sounding through a bullhorn.
Totally with you there !!
 
After a ton of research I've purchased 2.5" Dynomax Ultraflo Stainless Steel mufflers for my 70 Roadrunner. I bought the longer ones that will fit perfectly with TTI's header back H pipe system (Dynomax Part number: 17289, I believe). Right now Amazon has the best price by far on these right now which is why I went ahead and purchased them even though I'm a year or so out from doing the exhaust. Look up TTI they have a great reputation and are less than what you're quoting.
do you mind sharing some sound clips.

After another day of driving with my cut outs, i think Im just gonna opt to remove them, and do a full system from the headers. I just now need to figure out something that sounds like a true mopar / not too loud, but loud enough to sound like a muscle car. I'm leaning towards 2.5 inch vs 3?
 
For a mild 383, a 2 1/2 system is more than enough
In my opinion, the "mopar" sound was a bit more prominent than Ford or GM muscle, due to the "hemi" mufflers that were on most of the muscle mopars.
Hemi muffs were a 2 1/2 in/2 1/4 out triple pass.
If you want similar sound, but more volume (again, imo) shorter that hemi muff TURBO's should give you what you want.
I'd get a generic 2 1/2 header back system from Jegs or Summit, probably with the supplied turbos, and have a muffler shop install for you.
 
Dyno max Super Tubo mufflers 17747 or 17748. Full length - triple pass.
 
Thanks 33 IMP, that's probably how I'll go to upgrade my existing 383 Mag exhaust too. It's currently running 2-1/4" pipes and I want to go with 2.5".
 
I would leave the 2 1/4" pipes if they are good. I had flowmaster 40s and one side broke a inside weld they did have some years on them.
Anyway I went to Summits sight and ordered a set of their short single chamber turbo style muffs.
At the time they were aprox $39 per.
They are loud , I like them .
I have 2 1/2 pipe but I don't think a 1/4 is going to sound much different.
Jmho cut outs only sound good right at the collector.
 
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