Can't answer the question as to the "actual" gains you might expect from after market coils. However, I have my opinion, and the HP vs $ return IMHO simply is not there. At least in my case anyway. I suspect there may be a plausible reason to upgrade if you are pushing very high HP / boost levels, but even there I suspect the OEM coils can still push an adequate spark across the plug gap.

I replaced my coils with OEM Porsche parts (Beru). There was an update quite a few years ago and they are actually 997 model coils. If you can't find them for $40 EACH, send me a PM and I'll tell you where I found mine.

 

Buy almost the same kit from Dan @ Vivid more than a year.
Still amazing

 

Thanks for the advice dog4delta. I'll probably do this when I replace my plugs...

difparis, what is your boost pressure? Do you max out at 1 or 1.1 bar. How reliable has your car been and did you need a new clutch?

 

Regular boost pressure: 1.1
Max boost pressure: 1.2 or 1.3 depending on temperature (1.3 when it's under 11°c)
The car is very reliable. I think it can handle more. Don't forget that Porsche used that old engine for the 997GT2RS (and not the new engine of the 997TT MK2 )
For the moment, I don't need to change my clutch but I don't release the first gear at 5000
You can for that bundle with no problem. I gonna love it!