i hate people who lie and try and rip off people.This is a prime reason why you should of took someone who knows about cosworth's with you.
Yes it will feel fast, most cossies do, especially if you havnt had one before. if you were in a proper 460+ bhp cossie you would realise how fast that really is.
hope you get it sorted.
get it set up/and looked at by a GOOD TUNER, and then enjoy it.