What practices can aid (or not ruin) the mahasi style meditation? This question goes specifically to theravada insight practicioners - but everyone  can answer if they think they have something useful to add - even from other traditions

since my mahasi style practice is going slow and even though i tried in many ways  i cant maintain a steady practice - and my doubt increases - i want to freshen up my practice - maybe get some "results" wheter its improvement in concentration or metta or some "cool" results like seeing images or feeling strange stuff ect  

i wonder : 


whether some practices can ruin my main mahasi style practice (which i want to keep as my main path cause i have access to teachers in it) maybe kundalini and third eye and stuff like that can ruin my practice ? 
whether  some practice can aid in my practice - im pretty sure metta can be helpful but maybe pure concentration focus can distract me and do more harm than good to my practice ?  
i read that some food can be good for opening the third eye - can this food be helpful to the practice of insight meditation as well ?
The easiest thing to do to aid in your practice is to stop being so scattered!  Pick one technique and stick to it.  That you're all over the place exploring other systems and looking for results indicates to me that you are having a hard time staying focused on the cushion.  Trust, trust, trust in the process!  It's the only way you are going to make any progress.