There's some flex piping on my 04 Mazda 6s way up in the front of the car (I think it's part number AJ19-40-500G according to http://www.mazdamotorsports.com/pdfs/collgd/mz6_0304_cg.pdf) that is rusting and will need to be replaced. Is it really a pain in the ass to replace this part? Can you cut out the flex pipe and weld a new one in or would I need a new exhaust from the engine back? What are we looking at in terms of cost and labor hours?