Downsides to ECU Flash...
I've been researching the ECU Flash as well. In fact, I just about pulled the trigger with Powerchip. Only reason I didn't was because they started ignoring my inquiries on "the next step" to purchasing ECU Flash. Anyways, from my research I've come to the conclusion that engine reliability in years to come after the ECU Flash is relatively unknown. I mean if you only plan on keeping the car for 3-5 years, you should be good to go. Any longer then that and you're stuck with a big fat "?". Why?
1.) I don't think anyone has had their ECU Flash for longer then 3-4 years.
2.) How extensive could ECU Flash testing be from these well known tuners? E9X M3 has only been out since late 2007.
Of course, I'm not in the tuning industry so I don't actually know the rigors of each individual tuners testing or if it's even possible for them to test engine wear/life/reliability with ECU Flash after 100,000 miles, etc. This is just the conclusion I've come to after reasearching the ECU Flash for our car.
Also, initially I though Dinan's ECU Flash was wack because of the lack of power gains compared to others but after further research Dinan might not be so wack afterall. It seems to me that Dinan's software is used more to compliment their exhaust systems and charge pipe/intake i.e. changing the air intake and exhaust flow parameters a little. And at the same time making some minor tweaks to the ECU that BMW didn't due to emissions regulations. Yes, their ECU Flash doesn't create as much power as others but maybe there's a reason for their conservative approach, just like there's a reason why BMW tuned the ECU the way they did. Still, my 2 above points apply to Dinan, too.
Now I'm not saying that all these tuners are no good or anything of the sort. Just that engine reliability and warranty matters are kind of up in the air once you do the ECU Flash. Trust me, I want it hella bad, too. Another thing. Guys, don't tear me a new asshole if I'm off in any of this that I've typed. This is just my opinion. Hope this helps...