I just sold my 2007 Mazdaspeed 6, has the DI 2.3 turbo engine init and had some EGR issues, I usedit as my DD mainly back roads to and from work. Right around 45k miles I started have the check engine light pop up. Read the code and it was insufficient EGR flow. Did some research and found that this was common on these cars, and the fix was seafoam. Been using that stuff for the past few years in almost anything with an engine. It great and once you get some miles on the engine I would do a treatment on the intake before every other oil change depending on your internals. I did that and then went and ran the car pretty aggressively and took care of the issue until the next time, at which point I did it again. Take it for what its worth but thats what the mazda crowd is doing.