Well by law the pipe must clear past the cockpit area, Just what you consider the cockpit area is proably up to you and the guy doing your state insoection, your state, and or your local police officer handing you a ticket for screaming down the street. I failed my state inspection in TX because my pipes did not meet requirements, but then a trip to another sticker station and it passed. So proably not a big deal but something to think about. Nothing sucks worse than going crussing and the getting out and reacking like exhaust fumes. I was running 40 series on my 66 and would scrape on every thing. I took my floor boards and cut a section out roughly the size of the muffler in the rear area of the floor pan and took some 18 gauge sheet metal and used my sheet metal brake and made a box pan. I raised the floor boards up in the rear so i could raise the hieght of the mufflers. Solved most of my problems but i would still scrape on big bumps if i took them straight on. I never had backseat passangers so it was no big deal, but if you did I dont think they would be to comfortable because it did not leave alot of room for their feet. Just another option to consider if you have clearance issues