Daesun,

Despite the fact that I'm (sadly) *NOT* being compensated by RENNTech for the free advertising, I do, in fact, much prefer their chip to the PAD offering.

Perhaps I'm psychologically biased, given the *HUGE* price difference I paid; however, I can say this, factually: my gas mileage *slightly improved* (2-3 MPG) with the RENNTech chip (as compared to the PAD chip). Marginal, but true.

Don't ask me why: I haven't delved into the binaries to figure out what may have caused the unforeseen benefit. Moreover, this side-effect may not manifest itself in others' vehicles. All I can say is that the RENNTech chip does the trick. I haven't dyno'ed my 500E, so I don't have any concrete data to share.

I'm not a certified MBZ Factory Technician; however, when it comes to brand loyalty and technology integration projects, my personality is such that I prefer to keep things as homogenous as possible with products from vendors who have stood the test of time. I value quality and industry-proven results. I like AMG and RENNTech not because they are the most expensive - but because they are the best at what they do, in my opinion. I don't performance-tune Mercedes-Benz vehicles, and they don't subnet Ethernet segments and implement BGP routing policies and fully meshed topologies in data-center environments.

; )

In summary, "caveat emptor" always applies - especially for something as difficult to measure as software performance. To me, it is analogous to asking someone how fast Windows XP runs on their (fill-in-the-blank) dual-CPU microcomputer, and if/why they prefer it to Solaris 8, running on a single-processor Sun SPARCstation 5. The context is the key, and (as such) the dependent variable.

I highly respect all tuners' efforts and product offerings. I think, empirically, it just boils down to individual preference. I apologize for not being able to provide more quantitative/less qualitative data, here; however, I am sure Bob Brady (@ RENNTech) can provide you specifics/a "white sheet" to sate your appetite for facts...

If you wish to chat, further, about this - you may e-mail me at: nemo@nemonis.net

Kind regards,