Why dont you stop guessing and posting videos on the internet and just take it someone who knows Skylines??? Perhaps the guy who mapped it if he knows it so well?

I am guessing it was sold for 4K for a reason? Assuming it was the person that had it modified sounds like they got out of it because they knew what was wrong and needed doing and the likely cost??

Awesome cars though. Had one about 10 years ago and loved it. Hope you get it sorted.