some rag wrote the air cleaners "straighten the air intake path" and running one without disrupts the airflow......??? If you got one, run it. Little if any gains I guess, but loads of benefits.
I build my own exhaust systems too, (not that it has anything to do w/ this thread), but on a really hot 406sbc vega, pulling the exhaust system off , made .003 diff. w/ open headers. I think that was because of the weight diff.. I always leave the k-n 14 x " thick as possible" air cleaner on too.
