My friend has a D16B6 and he just got ahold of an SI head, the guy that he bought it from says that the piston rings in the block that the head came out were from a del so. Now this guy told me that in order to swap the heads he has to put delsol rings on his pistons in order to make up for the displacement or some shit, does this guy know what hes talking about or can he just swap the head

 

D16b6 ?? Havent heard of that engine code...

If it's the sohc vtec engine, that head is probably the same as the one he took off.
If he's trying to put a dohc si head (b16a) on his d16 block then good luck...
Piston rings don't have anything to do with what head he's running, compression ratio, or displacement....
if the head is the same then yes just swap it.