Some of the better equiped shops have a cnc pipe bender, If they have the program to bend your pipes. I saw a U tube a while back on bending pipe. The guy used several layers of duct tape on the end, then got on a ladder and used a wood closet hanger pole and WET sand and packed it in tight then duct tape layers on the top end. He then used the HF pipe bender. 50 plus years ago I tried the packing it with dry sand, and heating with a torch and it didn't work . We were putting twin pipes on a chevy 6. I bought a new stock pipe then made the necessary cuts and welds to have the second pipe fit. easier than building the whole thing with U 's and straights. 40 years ago we did an all nighter in a muffler manufacturing factory in the bad area of detroit. building a new exhaust for the 427 Cobra that won the 2009 optima That exhaust has since been replaced, . I used 1/8 gas welding rods to get the pattern shapes we needed then loaded the pipe and manually bent and rotated the pipes to get all 8 pipes bent.