No oil cap = more boost?

[tico915007]

I feel like an idiot but here it goes.....This is a 2007 STI mods are HKS catback and Cobb Intake. Maybe someone can help, yesturday I was adding some oil to my car was missing half a quart. To make a long story short i was in a hurry and i left the oil cap sitting on my intake manifold for about 24 hours unoticed obviously. While i was driving the car i was amazed to how much it pulled it had its initial jump but instead of staying consistent after 5,000 RPM it kept pulling like a champ. Thinking i was going crazy i took my buddy for a drive and he said my car felt faster and this morning my Girlfriend asked me if i did something else to make my car faster...... I finally notice my oild cap was off check my oil lever and it was fine. My question is does running with your oil cap off release presure in the motor allowing you to inadvertly run more boost or am i going crazy..... On my car before a 2004 gto i know when people were running boost on them the got a breathable type oil cap to releave crankcase presure is this so on our car?