[Darren69]

I have a full Termi on my S4 which is a 45 to 50mm tangential system and its good for 10% more power; mostly in the mid range. Its running a PCIII custom map to overcome the standard DP map leanness and I would think its probably one of the best mods to make on an S4. It sounds incredible too which is a bonus. That said I would think that a 45mm header would be a step in the right direction too, most are strangled by the 40mm headers even the M900/900SS.