Exhaust help 2.5 vs 3"
 

So the time ol question of 2.5 vs 3". I have a 66 lemans and building a 461 stroker for it planning around 500 hp nothing crazy. I have kids and a wife who will be riding in the car also. I previously bought a flowmaster 1041 3" kit but I'm having second thoughts. I don't want obnoxiously loud and a lot of drone and think going to 2.5 might be the way to go. Fortunately I have a friend also building a 67 who will take the 3" kit off my hands if I choose to go with 2.5" so.i want be taking much loss. What are your thoughts.

500hp is fine with 2.5" pipe and some longer mufflers on there for the family. Forget the flowmasters. A 2.5" pypes pipe kit and their quieter option mufflers - or get mufflers then from dynomax or borla - for a good no drone sound.

I would go 2.5” not only to reduce the sound level but for ease of fitment as well as ground clearance.

Flowmaster mufflers never on a street car but their aluminized steel mandrel bent 2.5” exhaust kit is very nice. Get the Dynomax 17749 Super Turbo mufflers and you’ll have the performance you want and keep your family from hating your car. :)

Copy that. I was never considering running flowmaster mufflers after watching all the engine masters episodes and reading this forum. Looking at either the flowmaster 817412 and then selling mufflers for some money back as I like the side exit look or looking at the pypes sga40 kit with their turbo mufflers or flowmaster 17107 kit and getting some turbo mufflers. The problem.is I definitely want a good idle but I don't want obnoxiously loud just for the sake of being loud.

I have a 3" with X and Ultraflows and is is fairly quiet no drone and almost as much power as open headers on my 78. And that is even with the additional weight of the exhaust system. 525-550 HP. Having a 3" H 3" Flows and 2.5 mandrel tailpipes did hurt performance.

How much of a performance hit did you take?

I'm building a much healthier engine currently and I'm currently running a 2.5" mandrel bent pypes system with the pypes mufflers replaced with Magnaflows.

I have great ground clearance with this system, so if the performance hit isn't extreme, I'll likely stick with it.

Ok well I bought a flowmaster 817412 kit from their scratch and dent section on ebay for $600. Sold my 3" kit for $350 to my buddy and I'll sell the flowmaster super 40s from the kit for half price and probably gonna try out the cherry bomb salutes which are essentially a magnaflow knockoff and are $36 each.

Scratch the cherry bombs I just saw how much cheaper the 2.5 inch dynomax super turbos are. I wrote them off on the 3" because I didn't want to spend nearly $150 per muffler, the 2.5" ones P/N 17734 are only $60 each. Much more palatable.

The 17734 are only 14” long if I’m not mistaken, noticeably louder than the 20” 17749.

I had the 17734 mufflers on a ‘76 T/A and they were fine because that’s all I had room for under the floor pans but on a Le Mans I’d get the bigger quieter better flowing 17749s.

I bought a merged exhaust recently for one of my VWs and coincidentally it came with a 17734 muffler. :)

I picked up 2 17734s for $32 & $38 on the 'Other Sellers' discount tab. Not installed so no reviews.

Well my thought was that I dont want it super loud but I do want people to know its not stock. So I figured that the shorter ones would be a little louder but still reasonable. Do you really think the longer cases flow better?

The 17734 and 17749 were both tested in Jim Hand’s muffler shootout and the 17749 mufflers made more power. The bigger case was less of a flow restriction, bonus they’re quieter as well.

When I ran the 17734 mufflers on my T/A I had 2-1/2” pipes to the mufflers and 2-1/4” tailpipes. The car sounded powerful even with the 7.6:1 compression somewhat anemic 185 hp stock 400.

Pushing close to 500 hp they might be too annoying, that’s my take. The camshaft in a 500 horsepower 461 will provide the sound, overly loud mufflers will not be necessary

Copy that b-man. Sounds like I'll go with the 17749 ones.

Just curious as I'm driving my self crazy listening to sound clips. Does anyone a have a magnaflow style muffler and/or a dynomax super turbo sound clip or video on their car?

What mufflers?

That video is with super turbos 17770

Thank you

Can anyone confirm the newer super turbos are full size are the way through. Was looking at the 17749 and 17734 options and saw some reviews saying they neck down to 2" inside. Any body else know for sure?