03 Cobra - Loud pop then odd noise from motor

First, a quick description of the car:
2003 Cobra, 21K miles (I know, not driven nearly enough), fairly basic upgrades including air intake, Accufab TB, 2.8" pulley, Bassani X and Cat-back.

As I was driving home today I was slowing down around a highway feeder entry ramp, when I heard a LOUD pop sound. I immediately thought I had run something over, but saw nothing. The clutch was in and I was braking gently. About 15 feet later as I was still slowing, I started to get a whine from the engine very similar to a pulley bearing failing, so I pulled over. Couldn't find the source, shut the car off, turned it on, and it seemed okay. I nursed it home without hearing the noise until approaching my driveway.

Once home I was able to pinpoint the noise, I think, to the REAR of the engine, on the passenger side. As much as I hate to say it, it almost sounds like it is coming from the passenger side head.

Has anyone with a 03/04 ever had a bolt fail in the cam journals?

So far, the car seems to be running fine. All gauges read like normal, and the idle does not seem to have been affected. The noise does seem to change accordingly with the RPM of the engine.

I am really hoping I misdiagnosed the source of the sound. I have replaced pulleys on this car and my Jeep, so I am familiar with that sound, and I have had an exhaust leak on the car and a cracked manifold on the Jeep, and did not get quite this sound. Needless to say I am a little freaked, especially since there was a loud pop or crack sound prior to the new noise, but I have not yet begun to pull anything apart. Any suggestions?

My plan so far is to start with the usual suspects by double checking the idler pullies, but after that my only plan was to begin pulling the inkate system to get access to the passenger side spark plugs. I really thought I'd be doing any intenal engine work on my 130K mile Jeep first, and I hope that is still the case.

EDIT: I did just double check the TSB/Recall info and read the report on the head replacement. I guess my first step will now be to call the dealer and see if that is the issue, since my car was built in Sept 2002. Can't hurt, right?

Best I can decribe it now is a ticking. Not real loud, but audible inside the car at low speed. It does eseem to be RPM dependant, like a pulley bearing failure would, so that will be my first step. Try the easiest to access and fix parts first. My plan is to spend some time after work trying to narrow down to possible causes.

The POP before hand is what has me concerned. It was immediately before the ticking started, so I sincerely doubt that coincidence is a possibility.

I have had it since 9/2002, so the 3 year warrentee is looong gone. My current plan is check the easy stuff tonight then take it to a Cobra pro on Saturday.