Anyone running 3.5" or 4" exhaust?

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chadtn

Not-quite-so-new-guy
Dec 23, 2008
28
3
3
I've got a 78 Buick Regal and was wondering if anyone has real world experience running dual 3.5" or 4" exhaust. Is there enough room under the car to clear that size of pipe at the stock ride height? I found one company advertising 4" oval piping, but they never responded to my messages. Has anyone else run something similar?

Thanks!

Chad
 

565bbchevy

Geezer
Aug 8, 2011
9,591
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Michigan
I made my exhaust using 4-1/2" pipe through the mufflers and then reduced it to 4" to get it over the axle, I raised the rear floor boards for clearance but the tail pipes fit with smaller diameter lowering springs and aftermarket control arms.
I did the mock ups for the tail pipes using 4" dryer duct and then ordered the mandrel bends I needed to make them and added V-band clamps for easy removal.
IMG_0134.jpg


 
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chadtn

Not-quite-so-new-guy
Dec 23, 2008
28
3
3
Very nice! You've got everything tucked in and fitting great! From the video, it looks like the bottom of the 4.5" pipes are about even with the rear sway bar. I wasn't expecting to have that much room under there.

Thanks!

Chad
 

565bbchevy

Geezer
Aug 8, 2011
9,591
12,612
113
Michigan
Very nice! You've got everything tucked in and fitting great! From the video, it looks like the bottom of the 4.5" pipes are about even with the rear sway bar. I wasn't expecting to have that much room under there.

Thanks!

Chad
The tail pipes are pretty tight especially since my car is lowered but I was careful during mock ups and allowing for suspension travel plus everything is rigid mounted directly to the car, the engine doesn't move and either does the exhaust.
 

Nomad1779

n00b
Jan 17, 2022
3
0
1
I was always told it wouldn't fit. I have a 78. 2 inch is as big as the exhaust shop would be willing to go
 

565bbchevy

Geezer
Aug 8, 2011
9,591
12,612
113
Michigan
I was always told it wouldn't fit. I have a 78. 2 inch is as big as the exhaust shop would be willing to go
I believe they have kits you can buy up to 3" but bigger than that you will probably be fabricating it yourself like I did.
 

motorheadmike

Geezer
Nov 18, 2009
8,976
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Saskatchewan, Truckistan
I was always told it wouldn't fit. I have a 78. 2 inch is as big as the exhaust shop would be willing to go

Oof. Nope. Wrong answer.
 
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