Infiniti: Infiniti G35 Coupe: Spoiler or no?

I am going to buy an Infiniti G35 Coupe. I personally think that it
looks a little better without the spoiler. However, if it adds a
noticeable amount to the performance, then I will get it anyway.
Has anyone driven the Infiniti G35 Coupe with and without the spoiler?
How much of a difference did you notice?

Thanks,
palpatine