3) Exhaust systems...This might be a hard question to answer sorry...But, What are Cuttouts and borla plates?
I'm guessing you're reading our post about the group buy on exhaust cutouts...
What most of us DSM'ers do with our exhausts is put a straight 3" tube through, to reduce restriction. This is good for power but bad for going through aircare, as we don't usually run cats (I'm not speaking for myself here, as I haven't been through aircare in a long time).
Most of us when we go to air care have to get under our cars, take out our test pipe (hollow pipe we use in place of a catalytic converter), and put in a actual real life cat. Just for 10 minutes on the aircare dyno.
A better solution to this is what you call a cutout. We keep our cat and restrictive muffler in place, and put in a Y pipe just before the catalytic converter. When you want to be quiet and clean, you put an 'electronic cutout' or 'borla plate' over the open hole in the y pipe, causing all the exhaust gas to take its usual route through the catalytic converter and through the muffler. When you want to be loud and fast, you pull off this plug and the exhaust gas will just go through your downpipe and out the open end of the Y, completly bypassing the catalytic converter and muffler. This is because there is less resistance going straight to atmosphere through the open Y than being forced through the cat.
Hope this clears it up