1: Is it worth replacing my 2wd engine with one from an escos
2: Whats involved
3: Would I need a cat

 

1 depends if the Escos engine's cheap enough(as a 205 engine can run big power)!
2 change the sump oil pump and p/up pipe,engine mounts,inlet,crank shaft pulley(if it's got the v belt type on it),fly wheel and need to change your turbo damper also! that's about it of the top of my head
3 Cat's are year related so NO you don't need one!

hope that gives you some idea!

 

Cheers bud