I'm about to put stillen headers and pulleys on this week but decided not to go with an exhaust yet and was just wondering if there would be any back pressure from the headers without an exhaust system?

 

Nope, you will be fine - as in no issues. However, the number one restrictor in the exhaust path is the catalytic converters. So, that being said, you in all likelihood will not see all gains from the headers until you do the exhaust and cats. This is typically the case, but may not be spot on for you. Just depends on what you buy. At any rate, you will not have problems. Just consider doing the cats next.

 

headers let more exhaust flow... more = good