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Discussion Starter · #1 ·
All new exhaust. I upsized from 2 1/2”’ to 3”. The pipe right off the header is just touching the transmission mount / support. It’s not jammed up there and it’s not barely touching it like it’s going to rattle. Is this a problem? Do I need to go down to 2 1/2” until I get past the tranny mount and then back up to 3”? Thoughts? I guess I could take the pipe out and bend it in a little right at the transmission mount?
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I'd squeeze it a little to clear that part. Some exhausts have a flattened portion for clearance. You keep the same volume it just isn't round at that point.
I'd say use a Big Hammer but it wouldn't look pretty. You only need a 1/4 inch clearance. Mark it and ask to see if a Muffler shop can flatten just the upper portion of that pipe.
call them and see what they recommend.
 

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I'd squeeze it a little to clear that part. Some exhausts have a flattened portion for clearance. You keep the same volume it just isn't round at that point.
I'd say use a Big Hammer but it wouldn't look pretty. You only need a 1/4 inch clearance. Mark it and ask to see if a Muffler shop can flatten just the upper portion of that pipe.
call them and see what they recommend.
Agreed on the flattening out. Unlikely to harm any flow in 99% of vehicles. Watched Engine Masters take a sledge hammers to headers and not put a "dent" in the dyno numbers.
 

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Discussion Starter · #6 ·
I'd squeeze it a little to clear that part. Some exhausts have a flattened portion for clearance. You keep the same volume it just isn't round at that point.
I'd say use a Big Hammer but it wouldn't look pretty. You only need a 1/4 inch clearance. Mark it and ask to see if a Muffler shop can flatten just the upper portion of that pipe.
call them and see what they recommend.
Ok thank you! I’ll mark up both sides and see if I can get someone to bend them in a little.
 

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Just a flattened portion so mark the top and how long you'll need without changing the pipes direction or bends. Bills Exhaust looks like this see the flattened areas....
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Discussion Starter · #13 ·
People argue size alot, and its not something I plan to do tonight, so I won't get started. I have heard 1" of pipe per 100 hp. 5" total for 500 hp if that stands true. Run what you got, just know you'll be fine flattening it out.
Roger that. This is my first ever build so love the insight. I've seen the discussions on smaller vs. larger and what the engine 'wants'. I'm not going to be drag racing :) just want it to sound beautiful.
 

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Roger that. This is my first ever build so love the insight. I've seen the discussions on smaller vs. larger and what the engine 'wants'. I'm not going to be drag racing :) just want it to sound beautiful.
For a mid range daily driver I just make sure its large enough to not restrict, and sounds good. Let the track guys worry about single digit hp gains/losses.
 

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It’s dyno’d at 461hp. Too big for that hp?
Absolutely not. Good call on the 3 inch.

Take a hammer and dent that pipe in otherwise it's going to bump and clank on the cross member and drive you crazy. I guarantee it will not cost you any performance.
 

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All new exhaust. I upsized from 2 1/2”’ to 3”. The pipe right off the header is just touching the transmission mount / support. It’s not jammed up there and it’s not barely touching it like it’s going to rattle. Is this a problem? Do I need to go down to 2 1/2” until I get past the tranny mount and then back up to 3”? Thoughts? I guess I could take the pipe out and bend it in a little right at the transmission mount? View attachment 725988
View attachment 725989
Why don't you heat up the crossmember and use a ball peen hammer to put some clearance into the C-member? I did that for clearance for a shift lever on a Richmond 5 Speed / Chevelle combo, never looked back.

Long story about why that was needed, no need to bore you with the details. Just heat the area where the pipe is close and put a nice gentle "slot" into the c-member. No need to go crazy you have less of an issue than I did. Maybe a 1/2 inch gets you free and clear of interference between the c-member and the pipe. I think I have some pictures on a thumb drive somewhere. Just a thought for an alternative answer.
 
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