Spring loading

I WAS looking to install Lovells coil springs on my 2008 Lancer ES, but was told by Mitsubishi my warranty may be voided. I understand that if a product is not up to manufacturer standards it would void the warranty, but according to Lovells its product exceeds the original ratings by 10-50 per cent. Mitsubishi showed some concept vehicles at the 2007 Australian International Motor Show in Sydney, and one was an ES sedan that had aftermarket 20-inch chrome wheels and lowered suspension. If Mitsubishi can display a modified car it gives the public the idea they can make such modifications without fearing the cost of possible future repair, which in this case is misleading. Where do I stand?