Re: 90 degree design stolen from Buick
So basically, anything out of the ordinary results in a retarded spark. In American cars the fuel cut off (when you take your foot off the gas) usually results in an opened IAC (idle air control) to prevent the sudden change from triggering a puff of HC. As near as I can tell the CF engine does not have a separate idle air control but does have electronic throttle control to accomplish the same thing.
Pontiac also had problems with scattering 4T65E trans behind L67s until they started cutting the injectors during a WOT shift. Cars were slightly slower in a 1/4 mile but the warranty claims plummeted.
There are also various maps and offsets used on computer cars to adjust to various conditions but 100C (212F) coolant seems very low to be turning back the ignition. Mine does seem to run mainly in the 180-190F range. But most GM cars and my Jeep are happy at 225F (I'm not but they are).
Also it does not have VVT but does have dual intake paths, one for operation below about 3,000 rpm and tuned to torque and a shorter one for higher speeds.
Agree the stock exhaust manifolds are just an unturned log but with alternate bank firing, a tuned exhaust would not be difficult.
Valves are pretty mild, about a 1.94 intake equivalent (two 1.4s) and 1.6 exhaust but enough for about 6000 rpm.
V8s have always been difficult to tune well because you need crossovers. Ford fixed that in the Indy engine by putting the exhaust ports in the valley. This works in a rear engine car (just leave the pipes high) but is more difficult for front engine RWD unless you wrap the exhaust around the front of the engine.
But the key here is that you have to know not only the firing order but also how the manufacturer numbered the cyl. See http://en.wikipedia.org/wiki/Firing_order for a quick look at the many differences.