Help! '06 430: error code in 1 cylinder..Valve issue?

'06 F430 Spider, ~16k miles, not driven hard…Check engine light comes on, I dutifully take it directly to a local who, while not an authorized shop, knows their stuff and works on exotics of all types.
Computer says bad ignition coil, no big deal, not a pricey part/big surprise…After getting part, they install and…we are still getting error code, indicating ONE cylinder has an issue. Upon start, engine doesn't sound HORRIBLE…but…you can tell it's idling a bit on the rough side. Mechanic is beside himself, as if this were an older model (like the 355 which had valve glide issues), this would be one thing, but he is stumped as to how a 430 with this mileage could have an issue. He is theorizing a possible valve spring causing a compression issue.
Where we are: As far as Ferraris have come, he's concerned because ironically, the newer models make it much harder to take the engine out. He's told me I'm looking at 40 hours labor to go that route (and that's just to try to GET to the problem). I would REALLY love to avoid dropping $4k minimum to go on a seek-and-find mission.
Anyone familiar with an issue remotely like this? Be advised, I'm not a mechanic and don't even know enough about cars to be dangerous, but thought I'd throw this out into the forum to see if anyone could help. Thanks in advance. Please don't let me make my next exotic an R8! =:-0

 

To help address the above comments, I talked w/ my guy, and have advised him he can jump on to my thread to better fully explain.
In short, he HAS done a compression test, and it's indicated low compression in one cylinder. I don't know what machine or code #, but I will get that info posted. While I appreciate the legitimate worry that I may have taken the car to a rube, my ignorance in being able to explain the problem as a non-gearhead shouldn't be construed as incompetence or an overeagerness to take my engine apart on his part. So, I appreciate the concern, but we can call off the SnarkFest here. These guys are reallly the "go-to" folks for high end cars of this type in this area, were even when we did have "authorized" service in the area, and are not out of their depth.

 

Thanks for the manifold suggestion...again, I'm not sure this hasn't been done, and to be clear, there is no rush to take out the engine. It is just a situation where the "normal" causes/solutions aren't readily apparent, and I thought there was an outside chance someone may have experienced a similar problem. And certainly being stumped on a problem isn't limited to non-authorized shops, as I've had situations in the past (both Ferrari and non-Ferrari) where the supposed experts were stumped for a diagnosis/solution.

 

Yes, he has his own contacts, this was my idea, but his ego is not such that it wouldn't allow there may be someone other than him or his circle who might be able to contribute something useful to the situation. Not that it's apples/apples, but for instance I'm sure the first person who discovered valve guide problems in the 355 didn't immediately say, "Well, clearly this is a problem caused by the guides being bronze instead of steel!" ;-D

And of course, this being the Internet, I expect to run into folks who get their jollys talking down to people to display their superiority, but I also knew I'd run into nice people who would make kind, positive suggestions in an effort to help. Thanks!

 

Thanks for the muffler bearing suggestion. I will pass it along, and relay any further, more detailed information I receive which may help others in their understanding and/or diagnosis of this issue. And of course, once it is fixed, which will hopefully be sooner versus later, I'll post whatever the resolution turns out to be, so that it may help any future non-expert like me if faced with a similar situation.

 

Misfire Fuel 302
Compression test-->PSI 65% on cylinder two...Rest of passenger cylinder bank ~175%
Running leak down test today

 

Update: Leakdown test confirms initial suspicious, valve or valve-glide problem. Mechanic has seen this often from 355/360s, but this is first time he's seen it in 430, going "right through intake", not indicating any manifold issues.
Haven't felt this bad since I had to get my Mondial T-cab towed from an auto detailer and subsquently found out the shifting rod had been sheared. And to think, I was just starting to feel comfortable with this car's status as truly "reliable"...Just a (not so) gentle reminder that there is a price to be paid for not saying your "fun car" is an Accord ;-D. Oh well, no whining allowed, don't do the crime if you can't do the time!