To go up to 4" with thin wall tubing, you are going to need to go to a mandrel type bender of substantial size . Some used ones are for sale here...
http://www.hornmachinetools.com/usedrebuilt.html
Jeff


Quote Originally Posted by BigTruckDriver
I am looking into making custom exhaust systems,up to 4".I would like to do some smaller stuff like roll bars also.What brand and models do you guys use?
what would you recomend?Thanks