Crank walk is when the crank moves excessively beyond how it's meant to move (ie rotational and slight end-to-end movement). Didn't know Evo 4's were bad for it but any car can suffer from it. Usually happens due to fooked thrust bearings. Poorly made cranks on the Evo 4's perhaps?
At least that's my understanding of it, not someting you see very often!
What about the 4 with the 6 engine in it ? i think that would solve the crank walk issue and give a huge choice for tuning.
He also mentioned the r32 skyline GTR just now as they are all around the same price : evo 4, 5, skyline.