If the car currently has no CATS on it? Reason being is that I want to get them installed in the morning at around 8 or so (depending when they actually start) and the car be done in the afternoon since I have to go out with my girlfriend for her birthday. Anyone know? Thanks in advance!

BTW. the set up is a MAC O/R H-Pipe w/ MAC Longtube Headers if that makes any difference

 

No different than a welded muffler I would think... Shop will cut where they measure and weld the new ones in. Id say an hour total, if even that. They're very fast with these types of things... (exhaust shops are, at least) They just lift the car, measure, cut with a sawz-all and slice right through in seconds, then quickly weld the new piece in.