I wonder the same, seems like an isolated pipe for each bank would be better scavenging than putting in a crossover. Wouldn't that cause turbulence, and slow the flow? Bill & Tami Roddick 1964 Imperial Crown 4 DR HT 1972 'Cuda 340 (Tami's Toy) 1988 Cherokee Laredo 1995 Concorde ----- Original Message ----- From: "Joe Bachan" <jbachan@xxxxxxxxxxxxxxxxxx> To: <mailing-list@xxxxxxxxxxxxxxxx> Sent: Thursday, February 05, 2004 1:54 PM Subject: Re: IML: Two 75 Imperial Questions -- Vinyl Top Removal and Cam Profile > Pardon my ignorance but how does tying the two exhaust > pipes of a dual exhaust system together with an 'H' > pipe improve performance? > joe