[btwilson86]

It's generally considered that after 7 revisions to the N/A "M" series engines (that's why it's a "7M" engine), there is little improvement to be had without going forced induction.

To answer your specific question, most OEM parts are identical and therefore interchangeable between the N/A and turbo engines. Cylinder heads, crankshaft, connecting rods, valves, these should all be the same. I've been told that the exhaust cam is slightly different, although I have never confirmed that. Also, as you pointed out, the pistons are different. Turbo blocks have oil squirters and are tapped for 2 knock sensors, N/A's only have 1 knock sensor and it is centrally located on the intake side. There are numerous other differences, but the big parts are mostly the same and interchangeable.

I would not expect any performance increase putting aftermarket GTE components in a 7MGE, in fact I'd expect a decrease; the 2 engines have 2 completely different tuning principles, and what works for one wouldn't work well for the other. Most people (myself included) would suggest getting a 7MGTE with electronics and modifying that, and just enjoy the N/A until then.

As far as sites to buy from, other than eBay and the likes I've only shopped from Driftmotion for performance parts. Payment processing and shipping turn around is reasonable, and Aaron has been prompt at returning my emails when I've had questions. I bought my 57 trim ct26 turbo from them, and have been very happy with it.