So whenever my car is cold, and accelerating, the engine makes a bubbly noise. it's 100% not a fluid noise, it sounds like something spinning but not smoothly. It's 100% not the transmission because it does it even when I press on the clutch and give it some gas. It goes away when the car warms up. The car still runs smooth and everything. Its not the tires either 100%, I had them all changed, and balanced.

 

Could be the different cam timing used to heat the engine quickly. Nissan does this to avoid adding an air pump that's only used during warm-up. Cold engines need a rich mixture, cats don't like that so air is pumped into the exhaust ahead of the catalytic converters to lean the exhaust mixture a bit. Nissan saves money, weight and complexity by changing cam timing during warm up.