I've tried QMax before on the note I thought my car's FC is bad... RM300-ish last year to my potato 92p. Drove from KB to JB to Sing to JB to KB, before QMax, my SAFC2 shows my electrical system voltage is 14.2V, and my car FC is 14km/L... after QMax... more than 2000km traveled, nothing change. Seriously, not even the torq has some noticeable feel of 'powah!' to my butt.
On day 11th after installing Q-Max... went to the retailer where I bought it, returned it and exchanged (+ RM topup) for EBC brakepads...
I just improved my FC to almost 16km/l after swapping my open pod K&N + alloy air ram to the stock airbox + rubber ram (which also made my engine works at noticeable... cooler temp).