Well part of it of course is all about market, as a car gets older, its part prices goes down, such as the case for the E55 OEM parts and it's aftermarket, that especially sees this. Maybe down the road there will be a bigger reduction in pricing for LT headers and what not. Back when the E55 was brand new, nothing was cheap as well. There is a big price to pay to own the newest thing out there and start adding fairly new mods in a new aftermarket scene for a new car.

 

how about this video kleeman cls55 stg 4 vs c63 MHP tune/headers.
http://www.youtube.com/watch?v=O0CErtbm7YE