I have a 94 civic ex, it has a full evo2 catback stock cat and a header, when im at low PM 2-3 rpms cruising and i give it a little gas, it sounds like an old VW bug! I have had all the connections checked no Leaks, so WTF.

Could you be a little more specific?

I will be driving around town at low RPM in any gear between 2.5-4K RPM and i will give it some gas lets say an 1/8th of a pedal and it sounds like there is a leak, the sound comes from close to the engine, i can hear it over the exhaust coming from the back. ... does that help at all