There will be FA difference between a MAF tune and a MAFless one with moderate mods on a VE - big mods, then yeah, MAFless is worth it but with just bolt ons then it's really not an issue.
Modifications won't void the ENTIRE warranty regardless of what it is - if you fit aftermarket springs, then, obviously the part of the warranty covering the the suspension will be suspect, but engine, driveline etc will be intact - and so on. But you also need to consider that a number of aftermarket manufacturers and installers will have a warranty on their parts and labour - so where you lose the holden warranty, you gain an aftermarket one. The big exception to that is with tuning. That's more of a grey area - but if you go with a GOOD tuner, then the risk is minimal.
