I thought I read somewhere that if you up your exhaust size, the engine gets a bit leaner (I guess because less restrictive, so more airflow due to efficiency, etc). Anyway, maybe I didn't read it, but if I did, is this true and is it something to worry about, or only a big deal if you're constantly tuning for the best A/F ratio? Thanks.

Just curious if anyone has anything to say about this..

I've read about it when switching to headers, not from up sizing exhaust pipes.