What brand did you get? Whether it will be a total bolt on operation depends on whether you have a downpipe included with the CAT and straight pipe/u-bend delete.
If it is just the CAT convertor with the straight pipe/u-bend delete more work may be needed to get it all to fit. The stock downpipe from the exhaust manifolds to the input of the CAT convertor is welded on last time I checked. If it is a complete one piece unit with downpipe then you'll need the gasket at the exhaust manifold downpipe flange and one for the resonator flange. If the input of the aftermarket CAT is flanged you'll need a custom connection done by a muffler shop. Normally the CAT input on stock and aftermarket is just an open input pipe and will require welding. Some just need a u-clamp and may fit over the stock downpipe.
Checkout the link below. It is for a Random Technologies unit which comes complete with one piece downpipe, CAT and u-bend delete.
http://macgp.clubgp.com/howto/rtdown...tdownpipe.html