I agree with LHD220TURBO, as regards the ignition though, whilst coilpack is good, it is NOT a performance option, it came about due to cost and emissions, it costs less to make than a distributor etc, and it does give a healthier spark, which is needed to ignite ever weakening fuel mixtures, caused by tightening emissions laws.
It will not automatically cure a problem, despite what some think, your std ignition will be fine certainly at idle, it's at the higher end when on boost and the consequent massive rise in compression ratio(adiabatic) that weaknesses will start to show.
If you intend to stick to L8, which can do the job perfectly well when mapped correctly, I would go coilpack just for peace of mind if nothing else, less parts to go wrong.
Don't bother with closed loop, as correctly mapped it's not needed imo.
Personally I think the coilpack conversion is expensive, esp when compared with the price of some ecu's, but I expect there was an enormous amount of time/cost developing it, but as you alos want AL then would be the easiest to add on sort of thing.
tabetha