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'72 Muffler Question

USNA1969

Well-known member
Joined
Sep 12, 2005
Messages
93
Location
Maryland
Corvette
1972 Big Block/4-Speed
I'm looking to get Flowmaster 40's, but they come in various I/O diameters. My current mufflers have a 2.5 input and a 2.25 output. It seems to me that the smaller output negates any advantage I'd otherwise get from the larger input, i.e., more back pressure. Does that make sense?

Also, are there original style exhaust tips with the larger diameter? Any ideas as to where I find them?

Thanks for your help.
 

RUSS O'BLENES

Active member
Joined
Aug 23, 2006
Messages
29
Location
LYNN MASS.
Corvette
1970 BRONZE COUPE/WHITE 69 CONV
I'm looking to get Flowmaster 40's, but they come in various I/O diameters. My current mufflers have a 2.5 input and a 2.25 output. It seems to me that the smaller output negates any advantage I'd otherwise get from the larger input, i.e., more back pressure. Does that make sense?

Also, are there original style exhaust tips with the larger diameter? Any ideas as to where I find them?

Thanks for your help.
I HAVE A 70. I TOOK THE EXHAUST TIPS AND CUT THE ORIGINAL PIPE EXTENTIONS OFF AND OPENED THE HOLE TO 2 1/2 AND WELDED A PIPE TO THE TIP. LOOKS STOCK BUT ALLOWS YOU TO USE 2 1/2 IN AND OUT MUFFLER. EXHAUST SOUNDS GREAT. HAPPY MOTORING. RUSS
 

USNA1969

Well-known member
Joined
Sep 12, 2005
Messages
93
Location
Maryland
Corvette
1972 Big Block/4-Speed
Thanks Russ. I had the same idea but wasn't sure if it would work. My concern was that the heat from the welding would mess up the chrome finish on the extensions, but I guess that's not a problem.
 

GTR1999

Well-known member
Joined
Sep 4, 2003
Messages
1,146
Location
New Haven CT
Corvette
1969,1972,1975
I put 40's on our 75 and I just put 50's on our 72. The 40's are smaller and fit up inside much better, with a 4 spd they sound great. The 50's are longer and don't fit as well. I have one side a little lower then I like and may redo that side. You'll have to fab up a bracket to use the stock hangers. I used 2.5 in/out and offset inlet and center outlet. I cut the flange extension off the muffler and welded in a reducer for the tailpipe- a couple of inches isn't going to make a difference.
 

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