So I went to put mufflers on my 1971 Charger R/T (it's a beater, not a show car). I knew it didn't have a 3-inch exhaust, so I assumed it must 2.5-inch. Well, much to my surprise, I discovered it has 2.25-inch exhaust (dual).

The weird thing is that it is a former drag car, you can see the remnants of the roll cage floor mounts behind the front seats, and it has long tube headers. Maybe the second guy (non-racer) who owned it put a smaller exhaust on it or something

It runs okay at the track (mid-13's at 100 mph; 440 ci/400 hp/automatic/3.91s), but now I wonder how much the exhaust is holding it back.

I went ahead and bought some 2.25-inch mufflers just to get it back together, but there will probably be an upgrade in the future (probably next year assuming I don't have any big issues with it this year).

Greg

2-1/2" with good flowing mufflers is a size that works for a wide range of engines on the street. For a modified big block I would want that over the 2-1/4" sized pipe.

3" is ok too if the engine is pretty built or being raced. It's also noisy and a little heavier at the same time. 3" over the axle and out the back can be a tight fit on some cars too.

Stock could have been a 2.5 head pipe with 2.25 tail pipes. Flowmaster makes the mandrel bent 2.5 tail pipes if you have a local shop that can run 2.5 to the mufflers when the time comes.

OE was dual 2.25" all the way. Here's a diagram from my old Walker book. I also have a 440 Mag 71 Charger R/T that I picked up late Aug. It has dual 2.25" exhaust off the stock manifolds & some ??? mufflers that are very restrictive. In spring, I'm going to have a 2.5" dual exhaust custom-bent with H-pipe, I already bought a pair of Dynomax Ultra Flo 17289's.

I am guessing the guy who raced it wasn't doing it with the 2.25-inch exhaust if it was quick enough to need a roll bar, it must have gotten put on sometime after that.

I too will probably upgrade to a 2.5-inch exhaust, probably next year, if it gets through this summer of trips to work and an occasional test&tune with no issues.

Thanks for the replies.

Greg

I think your Walker catalog is wrong
2.5 on the 375 HP 440 b body cars is what I remember going from the manifolds to the muffs and then depending on the year of the car whether it got 2.0 or 2.25 tailpipes

1971 B 440

Accurate Exhaust

You’ll definitely want to open it up to 2.5 at least to the mufflers. I’ve had at least two cars I can think of, one of which I just redid, that had 2.25 pipes coming right off the hp manifolds. Just a penny pinch corner cut. With headers there’s simply no way I’d leave 2.25 or put it back. My current car felt held back just a tad, I went under and measured the pipes at 2.25, I needed new mufflers anyway so it was no question in going back to factory size at least to the muffs, and my exhaust guy is a wizard so I knew he’d bend up some good 2.5s over the axle, just like always on my cars. I could feel it running better in the way home.

I stuck with the manifolds on my 69 GTX last summer. Car is all stock. It has more power with a 2.5 system going all the way to the 2.5 tips. The super turbos did the best of any of the quieter mufflers on some flow test chart an exhaust guy did. Chart is floating around mopar boards. I think ultra flows were among the best or were the best if you just went on flow and not sound. I added resonators and it’s as quiet as a new car, which is what I wanted. Don’t overlook hangers. I got the 2.5 factory style ones from accurate when I ordered the tips. I no longer have the buzz from some interior parts at certain rpms. That’s all gone now. The cost was eye popping outrageous and worth every penny.