I've noticed a greyish smoke when at WOT or high rpm in my b18c1. The previous owner gutted the cat but not sure if this is why. Anyone know if a gutted cat could do this?

 

the cat might keep a little of the smoke from coming out but it shouldn't make that much of a difference. I wouldn't worry about it it just sounds like it's running a little rich which is a lot better than running lean. If you are worried about it I know some dyno places will also hook up an a/f sensor and you can see if you can get it evened out.

 

seems like more smoke that usual... had a b16a a while ago and never had this happen... anyone else?

 

I have no cat on my race car and have constant smoke coming out in vtec. Don't worry about it.
Only worry about it when it smokes at idle and regular driving and you can smell it inside your car.