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**MikeB** · 03-01-2021, 12:27 PM

I would not go from duals to single unless you can live with less power and poorer fuel mileage. Worst case I would buy some basic stock replacement Walker mufflers and keep the duals. Even then you will lose some efficiency due to the mufflers being "necked down" internally. It's called "restriction" and is one way to reduce exhaust noise.

Quick story: Stock 69 C10 with 307 2bbl, single 2" exhaust, OE-type muffler, and 1-7/8" tailpipe. It got 10-12 mpg all around driving. Went to 2" duals with turbo mufflers (that actually weren't too loud) and mileage jumped to 12-14. And I can't begin to describe how much more power the engine had. With stock exhaust, it sounded like it was laboring to maintain 60 mph. With dual exhaust, it was like it got a shot of an asthma inhaler!

I just remembered this: Back in the day, it was common knowledge that a 250hp/327 4bbl with dual exhaust would get better fuel mileage than a 195hp/283 2-bbl with single exhaust. Of course, that was if your right foot behaved responsibly! In addition to the benefits of dual exhausts, the 4bbl primary venturis were smaller than the 2bbl venturis for better efficiency.

03-01-2021, 12:27 PM	#5
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,429	Re: Stock quiet muffler recommendation. I would not go from duals to single unless you can live with less power and poorer fuel mileage. Worst case I would buy some basic stock replacement Walker mufflers and keep the duals. Even then you will lose some efficiency due to the mufflers being "necked down" internally. It's called "restriction" and is one way to reduce exhaust noise. Quick story: Stock 69 C10 with 307 2bbl, single 2" exhaust, OE-type muffler, and 1-7/8" tailpipe. It got 10-12 mpg all around driving. Went to 2" duals with turbo mufflers (that actually weren't too loud) and mileage jumped to 12-14. And I can't begin to describe how much more power the engine had. With stock exhaust, it sounded like it was laboring to maintain 60 mph. With dual exhaust, it was like it got a shot of an asthma inhaler! I just remembered this: Back in the day, it was common knowledge that a 250hp/327 4bbl with dual exhaust would get better fuel mileage than a 195hp/283 2-bbl with single exhaust. Of course, that was if your right foot behaved responsibly! In addition to the benefits of dual exhausts, the 4bbl primary venturis were smaller than the 2bbl venturis for better efficiency. __________________ Mike 1969 C10 LWB -- owned for 34 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 23 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!