Have any of you GXP owners noticed a fairly rough idle for about 30 seconds or so after you first start your car? Every time I start it I get this rough idle like it'* running on 6 or 7 cylinders and then it smooths out after about 30 seconds. Not really too worried but wondering what it might be or if others have noticed this. Any ideas?

Yea, mine idles in an "unusual" way for a moment of two when first started in the morning. Might be that it'* cold... or it could have something to do with the ignition system on N*... my understanding is that each pair of cylinders is set to the same coil and fires one ignition spark and one redundant spark... it may be that right after start there is unburnt fuel on the down stroke and maybe it'* detonating, after one or two cycles it clears out... I know I am not explaining this properly, maybe one of the resident gearheads can do a better job???

Yes, I get the same behaviour, exactly as you describe. However, I'm afraid to bring in in for service (see my post - "GXP Maintenence - where?"

I'm tempted to hook up my OBD-II scanner and record the startup - any gearheads want to tell me what to record and I can post the data (plots). O2 sensors?, intake parms, temperatures etc.

By the way chuck chuckwi11, what'* a "K&N Diop In"

A "K&N DROP in" is a replacement air filter for the stock air box.

Does it make a noticable difference? or do you need a dyno to tell?

Don't know how it would Dyno... "they" say the gain is 5-10HP. I noticed a little better throttle response and maybe a little better MPG. Overall, I think it'* better.