Andrew

Why did GM go from 2.75" down to 2.5" right before the stock mufflers and then down to 2.25" after the muffler? I always thought it was 2.75 the whole way.

At first I was concerned about losing some power because the shop installed 2.5", but after seeing the stock setup, I think it will flow better.

cicch95

How do they sound!?!??!?!

Andrew

The sound is mean, but when the rpm's are below 2k and the engine is under load, the resonance might be to much for me. The flow is also much better which is what I am after. Luckily, the shop did not have the tips in, so they just cut them right behind the stock muffler where the 2.75 goes to 2.5. That way I get about a week to drive it without any mufflers and see if I want to keep it that way or buy some mufflers that flows better than stock. After seeing the stock muffler, anything would flow better.


If I need to buy some mufflers, what would be a good set (no flowmaster or cherry bombs )??

shakedown067

If resonance is an issue, it seems Corsa is the only way to go... Personally I like it loud, so once I get an X pipe, I'll ditch the elims and go with MagnaFlows.

CAP94

I have eliminators also and love them. Took me a while to do it but it sounds great!!

Leftoverture

How short did they cut the pipes? It makes a huge difference when they exit out behind the bumper versus exiting under the car. So if they're cut as short as I think you're saying, it will be much quieter inside when the tips are on and they exit behind the car.

Actually, stock LT1 mufflers flow really well if you want it kind of quiet. My L98 has Flowmaster 40s and they sounds awesome with no resonance but I also have long tubes and a custom Y pipe. The best set up for maximum flow and no resonance is the Corsa but you will pay big bucks for it.

RollaMo-LT4

Well, I told you about that. Shift to a lower gear to keep the rpm's up and it's not quite as bad.

CORSA is the way to go for dealing with the resonance. Rather expensive, but their engineers have figured out a way to cancel the sound waves in a way the eliminates the resonance.

Lots of opinions out there about this subject though. What is objectionable to one person is "sweet music" to another.

Andrew

They are open just in behind the IRS, right where the 2.75 goes to 2.5. I talked to the shop this morning and they said that it would be much better once they put the tubes and tips on. They had to order the tips I wanted and did not want to bend up any tubes until they could line everything up. The shop is very picky about their work, so I was just fine with that. Right now, in 6th gear going 70 up a small incline, the entire car shakes from sound vibration. It feels like I am getting a foot massage!! My ears actually ring from the resonance. My old 79 had a very stout 385 with 2" long tube headers, 3" tubes, and Flowmaster 40's. That setup was quite as a Lincoln compared to this. The shop is going to tack everything into place and let me drive around to see if it is better before final assembly. I'm not sure that I agree that the LT1 stock mufflers flows as well. They may not be bad, but they are still very restrictive (and HEAVY). I opened the car up one time and it bounced off the rev limiter before I knew what was going on. With the stock mufflers, I had to push it. I do believe that some bottom end torque was lost, but is made up in the upper RPM ranges.

You did warn me!! The good news is that I kept the original mufflers and will put them back on if it is still this bad after the tubes are installed to the back of the car. I tried shifting down a gear, but I live just north of JC and climbing a long incline up the MO river valley, I was in 5th going 80 mph before the resonance went away (don't want to think what kind of speed would be needed in 6th gear). I am really a slow / conservative driver, so I was white knuckled the whole way. I could just picture what a police officer would say if they pulled me over and my excuse was, sorry officer, I had to go faster to keep the sound pollution down.

RollaMo-LT4

Wow, I guess I didn't understand that they didn't actually exit out from under the car in your original post. Once you get the tips to exit out behind the car, the resonance will be cut down and for the most part bearable. But you will still have some when you place the engine under a load in a high gear.

I know exactly what your talking about there. I took a nice drive along MO 94 yesterday along the river. I love that drive from Hermann to St. Charles. Lots of bikes and other Vettes.