Your VW Golf will fail the smog check if its emission system is tampered with, such as in the case where you convert from single exhaust to dual exhaust. The State will consider this an "emissions system tamper" and your VW Golf will fail the smog test. So... your VW will not be considered a Gross Polluter (although it might if its emissions are high enough; HC, CO, NOx) but it will fail the visual inspection portion of the smog inspection.
