Pros and Cons of An engine swap? and best engine to put into my 318ti??

[atree1337]

Hey guys i would like some more power(use to drive a 99 mustang) so im considering an engine swap.

What are the pros and cons of swapping?
What would be the best engine to use?

My concerns:
Will all of my sensors still work?
Will the check engine light always be on?
Mpg??
would i need to relocate the battery to the trunk?


Thanks