I'm getting custom exhaust done, but I'd like to put a flowmaster 40 series muffler in the stock location. Does anyone have this part number handy, or possibly know the measurements of the stock muffler so that I can find the one that fits? Any help is much appreciated

 

flowmastermufflers.com

 

You can use two different mufflers depending on what might be easier for your exhaust shop to bend the pipe after the muffler. If you want to you can go with either a Delta Flow 2.5" muffler or a 3". You can also use a non-delta flow 2.5" (#389-42541 offset in/center out OR #389-42543 offset in/out "mustang muffler") which will be louder than the delta's depending on how you set it up. The Delta Flow 2.5's are #389-942542 offset in/center out OR #389-942443 offset in/out "mustang type". The 3" Delta Flow's are #389943041 offset in/center out OR #389-943043 offset in/out. The Delta Flows are supposed to be quieter for interior resonance but I have the non delta 2.5 offset in/out with a modified full 3" pipe out the back after the muffler and it isn't loud at all and actually has a nice tone but not "noticeable" like an 80 series crossflow but then again this is my daily driver (92RS LO3/700r4). Now the Delta Flows are actually reported to be just as loud as the non Delta's except when your just sitting there at idle (lots of Jeg's sales people quoted that to me). Now if you want to get a 3 inch,save a little money,arent too concerned with interior resonance then you can use the Delta Force 3" (or larger) Race muffler #389-9430419 offset in/center out OR #389-9430439 offset in/out. These are both two chamber mufflers and the same size as the regular 40 series. They are street legal and not really too much louder than the non-Delta 40 series. There is interior resonance with them that can get on your nerves but it does sound different than other cars and still have that slight flowmaster sound untill you get on it! Then it sounds like ROLLING DEATH! I know because I had one on my 85 Z28 with a TPI 5.0 with a custom bent after cat 3" pipe and muffler #9430439. It didn't set off car alarms though. Contrary to most everyone's beliefs on here, most of these "race mufflers" ARE 2 chamber mufflers and most are very similar in size to the 40 series case. They just don't have an extra plate or angled baffle plate welded inside (either forward or rear). If you want to have the "flowmaster tone" then get the any of the 40 series and if you want it louder than usual then get a turn down put on right after the muffler and support it at that end by haveing a hanger made/modified (if the shop will do it). This should give you the sound you want and with out too much interior resonance if you go with a 3" Delta Flow. You may want to have the turndown clamped on at first to see if you can hack it while driveing and then get a piece of pipe bent for it if it's too loud later on. I'm about to do this little modification in about two weeks when I bolt on my Hooker 2460 headers,custom Y pipe and that same 3" Delta flow with a turn down at a slight angle on one of my 87 IROC-Z's. This should suffice till I custom bend a true dual 2.5" X pipe set up useing a modified mustang double hump transmission crossmember for clearance. The thing about the custom bent 3" pipe after the muffler is that some exhaust shops have trouble bending 3" and if the exit is in the center of the muffler then it might be easier for them. You will just have to check on it.

 

Wow... thanks man. I don't think it would have been possible to get a more complete answer :hail:

 

Holy smokes man, what a response. Welcome to the board, you'll truly be an asset.

 

Well actually I've been here for a long time and just don't reply to every post like others unless I think I can be of some help, that is why it says "Junior member". Because I'm not concerned with it. I'm 30 and in the last ten years since I got into thirdgens, I've built 3-4 cars and bought and sold probably a total of 10. But I've taken pics to remember/document them all to remember the pain! Like the time I changed the ground effects with wing on an 85' Z28 to 91-91 back around 93'........it still makes my eye's want to water up when I think of that car rollin away from my house for the last time ....................anyway where was I? For my most recent venture, one of two 87 Iroc's is going to be heavily modified. I've already changed the pump to a 255LTR Holley unit and a new sending unit. After I get the subframe connectors/roll cage welded in, I'm going to cut a U shape where the rear seats were and pull it up flush, then trim the excess sheet metal off and weld. Then two flowmaster Delta Flows will be placed there giveing me full ground clearance. This will be a race car but look stock. The 406 with fastburn heads and ram jet intake should be enough to thwart the blue oval kids