Does anyone know where I can call to have a piece of 4" aluminized cut to length and flared? None of the local exhaust shops carry pipe that big, nor do they know where I can find someone who does.

 

I see you live in MN. I do too, I know around the saint paul area nobody really deals with 4 inch or larger pipe. Check your local big truck shop (peterbilt, kenworth etc)

Where are you located at?

 

Try a big truck shop. Not many places can flare out a 4 inch pipe..

 

If you can cut it yourself (sawzall/hacksaw/grinder) then just get some straight pipe from either a local truck shop, or online. Then grab a band coupling and you don't need to flare one end. Nice part about them too is you can take it apart pretty easy, unlike a u-bolt type clamp. Places like jegs/summit have all that stuff.

Another thing is 3 1/2" EMT (electrical thinwall tube) is 4" o.d. Not cheap though, but sometimes contractors/supply houses might have scrap pieces. It's galvanized, but has a coating inside that will "scale" over time.