How much power will Spoon header add? I was thinking to do a complete exaust system and intake. The setup that I initially had in mind was DC Headers, Test Pipe, Greedy EVO2 Exaust and AEM Cold Air Intake. With Test Pipe installed is there any way to fool O2 sensor so check engine won't light up? Just in genereal what would be a HP increase doing intake and full exaust system?

Thanks,
-Vitek