Sorry for the question but I am not mechanically inclined at all and know little about exhaust... I am interested in purchasing a slip on for my 02'F4i but in looking at my stock exhaust it is one long welded piece. I can't just slip the can off. I would have to take the can and midpipe (which is all one piece) completely off. Is this typical?? Do slip on's come with a can and midpipe to replace all of this? I am not interested in anything that will require remapping. Thanks.