I have had a CEL and code P0300 pop up a couple times in the manner the OP mentioned, the local Mazda service rep says its most likely the EGR. The EGR is still covered under warranty if the car is less than 7 years old (in Canada at least). If I pay the diagnostic fee they will scan the car...
The exhaust, like all other parts sold by Ion were manufactured by other companies. Ion was based out of Calgary and this is who made the exhaust for them http://www.techworkseng.com/
It would be nice to see this exhaust made again.
I had to run 3mm spacers on my wheels cause the center caps kept popping off my back wheels, other than that my gram lights fit fine on the front and rear.
Its the same reason why car manufacturers build cars with under steer and not over steer, its safer. I cant find the results right now, but Im not making this up.
You may be able to accelerate faster with the winter tires on the front, but while driving the car will have much more stability in the turns which is more important. This was determined in testing by Michelin.