...hand me some sauce for that crow I'm about to eat...

3 years ago I posted about loving the change from 80 Series cross-flow Flowmaster to single 3" in/out Magnaflow on Berlinetta #1, with ZZ3-clone 350 & TH700. Still maintain the claims for that change, and still have the system on the current LS1/4L60E in that car, but now have a new Flow story to tell.

On the LS1/T56 Berlinetta, I originally planned on, and actually had installed, true 2.5" duals. H-pipe, twin Aero Turbine mufflers. Sounded great, but I was only able to route that exhaust because I installed a torque-arm-eliminating ladder bar conversion set-up. Well, that suspension system was a disaster, and reinstalling a torque arm required cutting off the duals. So, back to the drawing board.

That was last summer, and continued suspension issues (long story, not for here) led to parking the car until this spring. I got the suspension issues sorted out in time to get out to the first stick shift race in May, with the exhaust being just the Hawks LT headers w/2.5" collectors, Magnaflow spun cats, open pipes right about at the end of the transmission. With that config, it ran pretty well with the cool air we had that day, but we got rained out after 2 runs.

Traction was a problem, so I switched from light tubeless Hoosier QTP DOT's on alloy rims to heavier MT ET Drags w/tubes on steel rims. In the meantime, I wanted to be able to drive the car on the street, so I started a search for a quiet, reasonably-priced cat-back that I could have attached to a custom Y-pipe. I was pretty sure I didn't want a cross-flow muffler, certainly with 2.5" outs, based on my 80-Series experience and everything I've read here, and I didn't like the tips that came on most of the "popular" dual-outlet choices. In addition, this car is weird in that it has a trailer hitch (if you can believe that), which adds a twist to the tailpipe routing. I finally decided to give Flowmaster another chance with their Force II system - single 3" in/out, turn-down tip (tucks up but clears the hitch nicely), and reasonably-priced. I installed the cat-back, the shop fab'd a Y-pipe and connected it to the system (including bolted flanges for easy removal after the collectors without taking the whole system down).

As I had assumed from the testimony of others on this Board, this system is very quiet, even quieter than the Magnaflow on the other car (although admittedly it doesn't have the cats). That made me wonder about how restrictive it might be, so only track data would do (since I wasn't going to waste the bucks to have it dyno'd before getting the exhaust installed).

Using MPH as the defining power parameter, the previous 107.00 MPH in May at 6000' DA, 3550 pounds going down the track, compares to 103.4 last Saturday at 8300' DA and 3650 pounds going down the track (the weight difference being the addition of the full exhaust, and the heavier rear wheels/tires). For reference, the LS1/4L60E car was going 106.1 MPH back in May on the same day as the stick car went 107, and it was doing 103.7 this past Saturday - basically the same config in the auto car both times. So, the difference in MPH with the stick car can be explained by the changes in DA and weight. Wind was not a factor either in May or this past Saturday.

So, all I can say is if you want a good-performing, quiet, reasonably-priced cat-back, and are willing to go with the a-symmetrical look of a single outlet, the Flowmaster Force II cat-back is a very good choice for a mid-power (est. 350 HP) driver.

 

Never thought this day would come

 

You and me both...

 

I have said this many, many times. I love mine!! I like the one hidden tip a lot better then the 2 visible tips and the sound is great. Welcome to the dark side.



Mark.

 

My hatred is only for the crossflow 80 series on a stock vehicle. A single in/out 40 series is ok. Haha I've ran them all and even the 4" Top Ten Shootout muffler that flowmaster make sounds really good but not as nice as a 4" Dynatech bullet..

 

If you prefer tips visible, I can see why you would prefer 2...
I didn't want to see the tips, so the hidden 1 outlet system was what I wanted...
I had ordered from Summit and it was supposed to come with a Super 40 (or 44) but it actually came with a larger 30 series Race muffler... I'm happy with it too...
I heat Primered / Engine Painted the one outlet black

 

Hadn't thought about that. But, this car is silver, so...

 

Not the best recording, but the best I have:




It sounds better after it has warmed up a bit.

 

^^Sounds good. Mine also came with the 30 series race muffler, I like it better then the 40 or 44. My 2 cents.

Mark.

 

The muffler came in its own box within the kit, with p/n 53058 on it. If you look that up on Summit, it is called a 50 series "SUV" muffler. On Flowmaster's website, they call the 50 series SUV "3-chamber" and "mild sound", and have a picture of a '57 Chevy next to the description - guess I'll have to put a couple of them on the '57 when I get the LQ4 in it and running...

 

Do you have any cfm data on your new muffler? The biggest concern with running a single muffler is the restriction it imposes. Your mph notwithstanding, there could be even MORE in your single exhaust if the muffler you're using doesn't provide the requisite 2.2 cfm/ horsepower. There are very few mufflers out there that approach 800 cfm and are still quiet enough so as not to drive you (or the neighbours) crazy.

 

Yep, I heard they were going to change to a 50 series. I think the 50 series is quieter then the 30 series which is a good thing.

Mark.

 

I'm afraid I don't have flow data. That was my concern as well.