I've got a Bassani SS 3" si/so cat-back on my 01/5.4 SCab. In front of that is the Magnaflow Y-pipe (dual 2.5" in/3" out). Muffler case size is 5"x9.5"x24". Problem is that it is becoming a little too loud for my taste AND I noticed a droning noise at 60 to 70 mph which was not noticed till I started driving my daughter to and from college downstate.

"If it's too loud you're too old" comes to mind.

There is B-Quiet on all 4 doors and rear floor/back wall.

Bassani says"There is no way to eliminate the resonance. The Bassani mufflers are designed to reduce the resonance. This is a common occurrence with after market exhaust systems that are designed for additional sound and performance."

I have tried a Hooker resonated tip which was 3" in and more like 2" out, a no-name resonated tip off of EBay and the Bassani 4.5" tip that came with the cat-back. The resonated ones helped a little at best.

The point I am at now is to replace the muffler(not with Bassani) and try to leave as much of the rest of the cat-back intact. This brings me to the big question "Which muffler?"

Magnaflow stainless and the Spin-Tech Truck/RV are on my mind now. The ST # 8441 is 4x10.5x20" and the MF #14591 is 5x11x30" case size. Both are 3" si/so. Any opinions/guesses or smart answers as to which would sound quieter? I'd settle for a crystal ball but all the Gypsies are busy helping the guys in the Lightning forum.


Edit: The existing Y is a Flowmaster.

 

Chidiver,
I have the Magnaflow 14580 S/S , SI/DO ( 5x11x22 ) on my Expy and I love it! Just a LITTLE louder than stock, NO DRONE on the highway! Very smooth sound! To answer your question... the larger the case, the quieter its gonna be! But now I'm wondering ( considering that mine is just a LITTLE louder than stock ) do you want to hear it at all? I mean you are going to a 8 in. longer case than mine so logic tells me that it will be quieter than mine. Are you sure that is not the inlet to outlet dimension? Hope this helps!

 

Thanx HR,

I'm at the point where I just want it a little louder than stock with some sound only when accelerating. Still trying to figure out what path to take.

Being considered is an X pipe as close to the engine as possible feeding a di/so muffler in the stock location OR a Magnaflow Y pipe instead of the X feeding a si/so muffler.

I have no idea if there would be any gain to be had by even putting in an X pipe if I'm gonna use a single tail pipe.


This afternoon I ran a stripe of paint from the cats back to the muffler to find out where the hot spot is. That should tell me something. It's all gonna be replaced anyhow.

 

I have a similar problem with my setup. It doesn't bother me yet. But anyhow, I think it's because the actual muffler case isn't round, it has a flat bottom and flat top. The problem is resonance is amplified by flat muffler surfaces. If I were you I would first try a muffler with a round case. It prevents any surface area of the muffler from vibrating because it's much stronger. You want the sound to come out the tailpipe and not out of the muffler's skin.

Otherwise don't use a straight-thru muffler design. Go with a "turbo" style inner baffling if you want quieter or the largest round straight through 3" SI/SO can you can find.

Different tips won't do much because the resonance is coming off the muffler.

To test my theory get something like a heavy piece or iron or something and buy a couple of really large stainless hose clamps. Put the extra metal on the muffler and clamp it down to the body of the muffler on the flat side or on both flat sides. This will act as damping to the flat surfaces. If you see a good reduction in resonance this way then you know for sure it's your muffler.

I have the flowmaster 2.5 dual in 3 SO y-pipe and a Dynomax ultra-flo and 3" single pipe with 3.5" stainless tip.

Good luck.

This is my actual truck and exhaust system install how-to.

 

Update

I ordered a Magnaflow 3" si/so 5x11x30 and a new Magnaflow Y pipe. The existing Flowmaster Y had all 3 ends welded so it's probably best to start over and move the Y as close to the engine as possible, as opposed to welded to the front of the muffler as it is now.

Muffler is on back order so we'll how it all plays out.

 

so how old is your daughter?

j/j

 

The one mentioned is 19. (She has a couple of tatoos.) She has a younger and an older sister.

Magnaflow Y pipe came today...Still waiting on the Magnaflow 14591, which is a 5x11x30 3" si/so.

 

Oh boy!

 

I kinda know where this one is headed.



FL, straighten him out will you please?

 

Hot damn.

Feel free to show them my pierced nipple pics

 

You don't need any tattoos!

 

I know I don't need any tattoos, but I want one or two.

 

How about a tat of a grenade around the nipple rings? You'd be the hit of the locker room.:santa:

 

haha, yeah I thought about that.

So what's your daughters look like



:evil:

 

Wouldn't do you any good other than to get you hot and bothered. One's grounded one day short of forever, one was #1 in her high school class and one is engaged. (You probably don't like smart women.)

Anyway they all near Chicago, prolly further than FL is.