I've got a '91 dx hatch with a DOHC 1.6L ZC swap and after I hit about 60mph the engine noise is loud as hell. It sounds like the engine is being over worked. I have an intake and a stock exhaust. 4spd tranny if that makes a difference.

 

Are you sure it's the engine? maybe it's the wheel bearings... My DX gets loud as hell when it hits driving speed too.

 

Oh, that's the "buy a B16" solenoid.