Here's a little bit about Flowmaster part numbers. In the 40 series, there is the "original style" and the "delta flow". The delta flow models have an extra chamber, and are *supposed to* cut the amount of interior noise. They do also cut the exterior noise though as well, and many people prefer the original, louder 40s. Flowmaster says they will sell the original 40 series mufflers while supplies last, and then the whole 40 series will be Delta Flow. The Delta Flows are still rated as "Powerful" (the loudest range), just a bit less powerful.
Having said all of that, in the 40 series, the delta flow muffler part numbers start with a 9, and the originals do not. So, a 42041 is an original style 2" in/out, and a 942041 is the delta flow version of that muffler. Disregarding the 9 in the Delta flow part numbers, here's how the remaining 5 to 6 digits work: A 42020 is - 4 - 4 inches thick 20 - pipe size 2 inches 4 - 40 series 0 - means the in & out pipes are both in the center pipe sizes are: 20 - 2.0 inches 24 - 2.25 inches 25 - 2.5 inches 30 - 3.0 inches pipe configurations are: 0 - in & out pipes centered 1 - in offset / out centered 2 - in centered / out offset 3 - in offset / out (diagonally) offset So, a 43043 is a 4" thick, 3" in/out, 40 series, with the inlet and outlet diagonally offset. The other monkey wrench in the mix is that the mufflers with dual outlets have a 6th digit. Their numbering works like this: 9 - Delta Flow 4 - 4-inch thick 20 - 2-inch inlet 4 - 40 series 02 - in-pipe centered, 2-inch dual out-pipes I can't seem to find a hard and fast set of rules that works for the last two digits of the dual-outlet mufflers. It seems that the 0 in this case, represents the in-pipe, being centered. Any even number in that place seems to mean that the in-pipe is centered, and any odd number means it is offset. The numbers do not seem to represent specific combinations of in/out pipe diameter, but it is true that (for example) a three-inch in-pipe muffler only comes with a couple of out-pipe sizes, and it seems they assigned numbers to them as necessary. A 925412 has 2.25 in and 2.00 dual out, and a 9430412 has 3-inch in and 2.5-inch dual out, so it's safe to say that the "12" does not represent any one in/out pipe size combination. Maybe there's more to learn on that. Well, there are some fun Flowmaster facts for you. Now you can look at the part number of any single-outlet Flowmaster muffler and know exactly what it is, and at least have a good idea w/ the dual-outlet models. John Nasta ----------------------------------------------------- To Unsubscribe please visit www.chevelles.net/list.html To start a new topic, send mail to: [EMAIL PROTECTED]
