Idle sounds like a tractor
 

I've heard this engine can be noisy at times, but after the initial warm up of the engine when it quiets down it sounds really rattly, like a tractor.

Revs up fine and otherwise drives great, but it sounds like an old tractor when it's idling. I'll try and get a video up but I was wondering if anyone else gets this at all?

Normal. Get an exhaust so it's rumbles like a true boxer should

Is there a different sound when your clutch is engaged? I feel like the trans is loud when in neutral, but when disengaged, the motor is smooth as butter.

You'll need an unequal length header for that, no axleback or catback exhaust will give you an authentic boxer rumble.

I believe it to be normal too. Anyone know what causes this? Its similar to lifter tick but only starts when the engine warms up

EXACTLY!

Good to know its not just me. It definitely sounds like lifters or a thrashy valve train. It's fine if you rev it up though and it's not present on initial starting of the car.

Allow myself to quote....myself.

Do this check when at idle and see if the sound goes away.

Direct injectors handle a lot of pressure. They make a noticeable ticking sound when in use. Could it be that?

Didn't make a difference for me.

It's worth noting that lugging the engine in second gear (below 2k rpm) often sounds terrible and very rattly.