I am buying a street 750 and i heard the sound with the Screaming Eagle exhaust and it is awesome. But the dealer is asking me to change the spark plug, spark pug wires and the air filter.Is this ncessary.

 

I wouldn't think you have to do everything the dealer wants to sell you, just to change the exhaust. Doesn't make sense, but I'm not that familiar with the Street to say for sure. You're in the Dyna area, so you might want to post in the Street section.
I think you have a dealer just trying to upsell.

 

Hey KKA,

I'm rockin' the Bassani pipe without the airbox mods. Runs great. I did change out the spark plug wires to the 10mm Phat SE. I really dig my 500 and I hope you enjoy your new ride!

Weshicatwelo

 

If you change both the exhaust and intake you'll need to have the bike tuned.

 

Which means more money for the dealer