3.5 was worth it...for me
1) i like to do things differently, and if i was going to replace an engine why not spend a extra time put in the biggest - am not saying bigger is better in all cases
2) engine was $425 with roughly 40k on it (couldnt find a 6g72 or 6g73 for that price with those miles)
3) when the 4g eclipse aftermarket gets moving there will be lots of parts

... what am interested in is rods (6g74 and 6g75 share the same rods) the 6g75 crank will also swap in (larger displacement)...etc.. there are pistions for the 6g74 already - "tearsome"...thru RPW
CMC