L-20B-nothing more than 2 inch is needed.LZ-23?2.5 is what will work best.Outlet,one size down from inlet size.Same out as in will net you nothing but noise.
This topic had a post from someone who posted a link that would tell you who(seller)had what parts(used) for the type of car you entered in the fields.I THINK it was a 210 thread.
Thanks.