What should I do for exhaust on my 250 I-6? Already have dual headers! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

71ChevySS(straight6) · 07-08-2015, 10:18 PM

Hello again! The headers I bought from Jegs have a 2.5" collector. Should I run with the 2.5" pipe, or go smaller?

A little background, if it helps: the engine, a 250, was pulled and rebuilt, bored and stroked, tuned up just recently. I'm sure it's pushing more power than it was before, but I'm not sure how much more.

I want to run dual 45s out behind the tires with an X-pipe so that each side doesn't sound like a three-cylinder. What mufflers should I run?

lowrollin70gmc · 07-08-2015, 10:31 PM

I run dual 2" thrush turbo mufflers on my warmed up 250 in my 63 Chevy II. No cross over, and I think it sounds decent and it does mellow out at highway speed, I've done multiple 2000 mile trips with no drone issues.

Click on the picture for a video of how it sounds with a stock 250, I don't have a video of the built motor.:

**special-K** · 07-09-2015, 07:20 AM

Dual pipes w/o crossover won't sound like tree cylinders from each pipe. I would use 2-2 1/4"

07-08-2015, 10:18 PM	#1
71ChevySS(straight6) Registered User Join Date: Mar 2013 Location: McPherson, KS Posts: 96	What should I do for exhaust on my 250 I-6? Already have dual headers! Hello again! The headers I bought from Jegs have a 2.5" collector. Should I run with the 2.5" pipe, or go smaller? A little background, if it helps: the engine, a 250, was pulled and rebuilt, bored and stroked, tuned up just recently. I'm sure it's pushing more power than it was before, but I'm not sure how much more. I want to run dual 45s out behind the tires with an X-pipe so that each side doesn't sound like a three-cylinder. What mufflers should I run? __________________ '71 Custom-10 2wd longbed, 250 inline-6, NP 435 four-speed. Medium Bronze Iridescent. Farm truck deluxe. Rat rod build: 1949 Crosley Station Wagon body on 1993 Dodge D350 chassis, Cadillac 500 powerplant.

07-08-2015, 10:31 PM	#2
lowrollin70gmc Too many projects Join Date: Mar 2004 Location: Fargo, ND land of the flat hills Posts: 1,147	Re: What should I do for exhaust on my 250 I-6? Already have dual headers! I run dual 2" thrush turbo mufflers on my warmed up 250 in my 63 Chevy II. No cross over, and I think it sounds decent and it does mellow out at highway speed, I've done multiple 2000 mile trips with no drone issues. Click on the picture for a video of how it sounds with a stock 250, I don't have a video of the built motor.: __________________ Andrew 84 GMC C1500 SWB 6.2 Diesel/700R4/3.42 "Grandpa's odd duck" 70 GMC C1500 LWB My first truck: shaved, bagged, and more: the lowrollin70gmc 68 K20 Suburban 12V Cummins/NV5600/NP205/D60/11.5AAM 3.73s "Dakota Cadillac" 63 Chevy II Nova Coupe 250 I6/T56/4.56s "Economy car" 53 Willys Wagon 350/NV4500/BW4401/HP D44/9inch “Winter Wagon” 30 Model A 16 Focus ST

07-09-2015, 07:20 AM	#3
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: What should I do for exhaust on my 250 I-6? Already have dual headers! Dual pipes w/o crossover won't sound like tree cylinders from each pipe. I would use 2-2 1/4" __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~



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