jetech

I am trying to decide on the 40's or 50's. I want to change my 77 to true dual's and am looking for advice on what part number to get. Also what size exhaust tube should be used on a slightly modified 350 with headers. :seeya

Surfer69

My 40s are 942442, I only have 2" pipe after headers but wish someone had used 2.5, oh well. Figure how you want to configure because each part no. has different input/output tube locations.

7vette2

Of course this is depends on how loud you want to go. I just installed Deltaflow 40's (PN 924440) on my stock '72 350 (2.25 dia. pipe) and I think they sound great. Loud, but not crazy. The standard 40 series are a bit louder and throw more interior noise. 50's are a bit too tame for me, but again it is a matter of what you want. You can check out the different types on the Flowmaster website. Good luck.

jetech

7vette2
The deltaflow 40's sound about right. I wanted to make sure I put on the right size diameter pipe for the engine/header combo. It seams like most owners are going with the 2.25" pipes.

Jvette73

The flowmaster 2.25" are 942441. Thats 2.25 offset inlet and 2.25 center outlet. There is a longer and shorter version of them, The shorter ones are 42441 I believe. The important thing it to get underneath the back of your car and try to visualize the routing of pipes to decide what length and what offsets will work best for your particular plan. I used the shorter version with offset inlet and center outlet. The shorter ones allowed me to mount them flush with the underside so they dont hang down on any angle of sorts. The shorter ones were required to allow enough room to hide them and still leave enough room fot the incommong pipe to turn down. when viewing from the rear the muffulers cant be seen. All you see it the tip comming thru the cutout.

Ice_Fire

Depending on the volume you are looking for is what you need to decide on.
Flowmaster Delta Flow 40's are loud and have a low pitch interior sound that get's a little irritating.
I am running Flowmaster Delta Flow 50's, which are 19" long ( case ) where the 40's are 13 " long so louder. I have 2.25" pipes with offset inlet and offset outlet. Sound clean and a bit throaty when idling at low RPM but still has a low pitch interior sound around 30 Mph, not as bad as the 40"s. Not to much sound at all on the Hwy though which is great for cruzin.