I got the car in Dec. '04, got my SB100 no. in '05 and finished it in '06. Absolutely no problems.
One tip on the smog part. You need to PASS a smog test, not just take one. That means that you need to be able to hold the engine at 2,500-2,600 RPM for one full minute. Also, it needs to idle for another full minute. Everything needs to be connected and it needs to have
oil showing on the dipstick. Also, it needs a functioning gas cap. The only way the inspector was able to get me through was to actually call BAR and ask for permission to "fix" the machine so that it shows "Pass".
This is all for you guys who have a big engine with a big cam, carbs, etc., who
really need an SB100 exemption. For those with 60's-vintage 289's. 390's, 427's, or 428's, you might want to use the regular SPCN registration route. You don't need an SB100 exemption, you just need to keep the smog equip the same as the engine year was.