I was looking to increase the power output and/or increase the MPG of my 2006 CLS55 AMG. Anybody out there have any suggestions/experience in this area? Reprogramming chips, etc. Cost?

 

I live in Denver. Any tuners or shops in this area that you could recommend?
When I put a Saleen supercharger on my 2008 Navigator is was a fairly "involved" process because I bought the kit from Stage3Motorsports in Phoenix, had a local dealership install it, and ultimately BBR Racing in Florida designing the custom tunes and having me download them via a SCT handheld tuner. Extremely happy with the results.......but it ended up taking 6 weeks and lots of coordination.
I want "one throat to choke" this next time around.
I was also seeing some of these "plug in" chips for ECM/PCM modules for Mercedes on the internet claiming 50HP gains and improved MPG. I was curious if anyone has had any luck with any brand/type or could substantiate any of the claims.