I'm looking for that same answer right now. No one seems to be able to do mandrel bends. Watson Engineering in Taylor is the only place I've found so far. The only do stainless and are booked until almost the end July.
I wish I knew. I would like mine done with an x-pipe but I don't know anywhere to take it. I'll ask around this weekend at some of the local cruise-in's. Let me know if you find some good deals and I'll put this post in the favorites if I find anything out.
Try the Muffler Man on 14 mile and Groesbeck in Fraser. The number is (586)294-0333 ask for Tim he is the owner.
I used to work there about 10 Years ago but he still has an extremely talented guy that can bend anything you need. When my car is done I will go there but I will bend it myself ( 20 years doing this ) just to refresh the old brain.
He can usually get stainless or galvanized so make sure you get the price for that and not regular steel. Stainless is really tough on the dies for the bender and unless you fill it with sand it will start to flatten on any bend over 35-45 degrees.
My first suggestion would be Watson. But you may want to try Livernois Engineering in Dearborn Heights since Watson is booked. Livernois also does exhaust fabrication for the automotive industry. They have a walk-in motorsports parts office at their Gulley Road offices. I have purchased some things from them, not the cheapest. But Watson will not be cheap either.
Does anyone have any suggestions on an automatic transmission shop in SE Michigan? I may have to repost this Q outside this thread!