2v/4v's are light years ahead of the 3v, sound wise. That's a big reason I got a 2v and didn't just finance a 3v.
Is it worth building? Well that's a matter of opinion. You can make any car really fun if you got deep enough pockets. 4v has a lot more potential, and is the favorite of the new edge era. But if you throw a power adder on a 2v that has full suspension done then it's going to be really fun! It might not be the fastest on the street but then again it will be yours and not the banks.
Idk about 4v, but the 2v will have to be fully built to take 600hp (if it will even make that) along with the trans. I can't remember which components, but on a 2v it can only hold up to like 450 until it needs built. The t56 (I think that's right) has a really good rep for being able to hold on to strong power.
Yes I edit my posts a lot, auto correct likes to sabotage me!