C2 exhaust 'Off Road'

[Justin N.]

Dear Members,

I see that Dr. Rebuild and Paragon offer the 'Off raod' exhaust mufflers with their systems. They're supposed to have one less baffle for a better flow with a slighter greater exhaust note. Has anyone installed one of the systems? How do they sound? I would like an increase in flow, but wouldn't use and don't want that Flowmaster-aftermarket sound for my vintage 67 small block. Thanks a bunch!

Justin #41362

[William V.]

Re: C2 exhaust 'Off Road'

Justin

I have the factory off road on my 64 365 and when I'm pulling 6000 rpm shifts it sounds awsome. If I'm not on it it's just a little louder than stock. Just want to remind you that the off road exhaust is 2 1/2 inch and if my memory is correct all 67 small blocks are 2" exhaust. You can work around this in two ways.

You can get earler 2 1/2 inch exhaust manifolds and change the entire system to 2 1/2 or get the engine pipes that go from 2" manifolds to 2 1/2" pipe. On the factory off road system the mufflers include the connecting pipe that connects to the transmission cross member. The muffler and pipe are one unit.

You should know that I only hear the loud exhaust sound when the top is down. All the sound is out the back.

good luck

[Joe L.]

Re: C2 exhaust 'Off Road'

Bill and Justin------

For 1967, only the base 300 hp 327 used a 2" exhaust. All other engines, including the L-79 small block, used 2-1/2" exhaust. However, ALL small block manifolds after 1965 were 2" outlet.

There is no reproduction muffler on the market today which is internally configured like the original 63-68 off road mufflers or, for that matter, like the 63-72 standard mufflers. Consequently, there is no reproduction muffler today that sounds like the original mufflers. The current reproduction "off road" mufflers are externally configured like the originals, but the internals are substantially different.

The original off-raod mufflers had a sound like the standard mufflers except a bit louder due to one less tubular internal baffle. The "reproduction" off-road mufflers of today sound like the "reproduction" standard mufflers, only louder, but they DO NOT sound like the original off raod mufflers.

[Jim W.]

Small Block '67's have a 2 1/2" exhaust system....

...when equipped with a manual transmission. Powerglide cars use a 2" system. I found the best one-piece off road exhaust systems were from Zeirden. Jim Weeks - Member #2978

[James W.]

Re: C2 exhaust 'Off Road'

Justin,

I purchased and installed a 2-1/2" off-road exhaust system on my 1964 Corvette. The system was from Allen's Stainless. It is the aluminized system and it fit well with little work needed. It is not loud at all, in fact it is quiter than the Walker brand OEM replacement muffler thay I removed.

James West
Omaha, NE.

[Joe L.]

Re: Small Block '67's have a 2 1/2" exhaust system

Jim------

Yes, you're correct. All 1967 Corvettes were equipped with 2-1/2" exhaust except 300 hp with Powerglide. For mid years, 2" exhaust was limited to all 250 hp (63-65) and 300 hp with PG. Although the for 66-67 the 300 hp was the base engine (as the 250 hp was for 63-65), for 66-67 the base engine with manual transmission used 2-1/2" exhaust.

[Justin N.]

Re: C2 exhaust 'Off Road'

Dear Members,

Thanks for all the help! Bill, I have switched my original manifolds to the current GM 2 1/2". I plan to have 2 1/2" all the way back to the stainless 2" tips. James, I thought those Dynomax/Walker mufflers would be too loud. Thanks again!

Justin #41362

[Jim W.]

Re: Small Block '67's have a 2 1/2" exhaust system

Joe, Thanks for the detailed clarification. Our original posts on this thread came in at the same time. Kind regards, Jim