Possible MSD 6al Problems

[AMiller]

So, Im stumped. Have a MSD 6AL on a 351 Windsor motor and MSD Blaster Coil.

Car runs good, starts well, and idles fine. Been noticing a pop sound at lower rpms in the passenger side exhaust.

Thought it might be an air leak. Changed exhaust manifold gasket and tightened the header to exhaust pipe connection and nothing changed.

Checked plugs , looked ok but changed anyway. No change. Changed plug wires, no change.

Noticed that the header tube next to firewall was not as hot to touch as other 3. Headers are wrapped so you can touch briefly without getting burned but cant leave your finger on the tube. The other tube was very warm but not so much that I couldnt leave a finger on for a time. Checked that plug again. Looks pretty good. It is firing. Maybe not quite as gray brown as the other 7 but close.

Also noticed that idle has dropped lately. Not much but enough to notice. Still idles fine but a little lower. The last thing I have noticed is the motor is not reving out quite as high as usual. Maybe only 200 to 300 rpm difference but its noticable.

Anyway, Im now thinking that the MSD box is the issue,just wondering about other thoughts and ideas???

Thanks Guys,

Aaron