My service engine light came on yesterday and the engine started intermittently running a little rough. I had a friend hook up a code reader and it reported a problem with cylinder 5 ignition system. I am assuming cylinder 5 is next to the firewall on the passenger side. Is it possible to replace passenger-side plugs and coil packs without removing all of the intake parts which are positioned above that side of the engine? The driver-side looks simple but the other side, not so much. What should I expect to pay if I had all of the coils and plugs replaced? I see that Nissan wants about $125 for a single coil whereas you can get a set of 6 aftermarket coils for that much (or less). The vehicle has about 120K miles.

You're correct about the location. The plenum has to come up to change the bank1 coils and it's not an insignificant job, so with 120K, you'd be wise to change out all six plugs and coils. The older Pathies are fairly fussy about coils if you're changing them onesy-twosy, but for replacing all six, just stick with a reputable riceburner brand. Most OE Nissan coils are Hanshin, but you should also be safe with NGK/NTK, Hitachi, or Denso (Hanshin is actually a Chinese collaboration with Denso). NGK and Denso plugs both work well in VQ40's, but they have somewhat different characteristics in both the platinum ('07 original) and iridium (upgrade) varieties. In general NGK's have tougher electrodes and last longer, but are not as resistant to fouling. Densos generally wear quicker but give noticeably hotter spark. So if you want performance, or if you drive like grandpa and fouling might be an issue, pick Denso. If you're an ordinary driver and want to repeat the job as little as possible, pick NGK.

VStar650CL - Thanks for the help. I decided to pay a mechanic to do the job. It's 95F here and today is my 77th birthday so call it a BD present. They are charging $380 to replace the no. 5 coil pack. They use Nissan parts so I guess they are hitting me for about $250 in labor. Seems like a lot but most of the videos I looked at showed a LOT of parts above the 1-3-5 side of the engine that need to be removed to gain easy access to that side.

That's 2~2.5 hours at most outside shops' rates ($100~125/hr), which is entirely reasonable for that job. There are a lot of parts to remove.