is the computer a little guy that looks like this ?
If so, that's the access port I was referring to. If you have that lil guy you're in much better shape than not having one, and that also means that if you need or want to you can go back to a factory downpipe and simply re-flash a factory or stageI map back on.
Before you do any of that though, check the downpipe for names/logo's and see if there's a decent sized bulge in it. let us know what you find.
fyi, if its catless.. that will explain the odd smell like an old car would have when it fires up. First cold start cars run very rich for a few seconds (same affect as a choke on a older car or truck) then even out as they warm up.