I'm a little underwhelmed with my Ntg-2/H4n combo.
Well, you buy low budget gear, you get low budget results.
I need to be at 100 recording level, and still I'll get -18 to -12 db,
The NTG-2/H4n combo is notorious for low levels. Production sound levels should be -12dB, with peaks at around -6dB.
the sound is a little artificial and muddy.
Artificial? Well, anything that is recorded is going to be artificial. The "secret" is in the skill set. It takes skill, knowledge, experience and some talent to capture solid production sound. A few questions for you:
Are you the one swinging the boom?
How close is the mic to the actor(s)?
Is the mic accurately aimed?
What settings are you using on the H4n?
What are you using for wind protection?
What headphones are you using to monitor on-set?
How does the dialog sound on-set?
What is the sonic environment on-set?
What are you using when you listen to the playback in audio post?
I was wondering if there is a good upgrade i could get for $500 or under that could improve my sound quality/sensitivity?
The ProMix 3 and MM-1 are good, solid additions to a low-budget sound kit; the improvement of preamp quality in your signal chain is definitely worth it.