EDGE VS all model from Entry Level > BT103 > BT 303 > BT 502 (this one not in list) are car battery Voltage Stabilizer.

All these can improve car performance and audio as well. Base on normal car condition, the higher level the more effect.
HUVS is Head Unit Voltage Stabilizer. Head Unit so call HU refer to car audio player. This HUVS design purposely for audio performance.

May I know what car you plan for the VS? 

depends on your budget. But GC is a must in your case 

many issue can affected car performance. throttle body .. air filter .. rim size .. spark plug ..
GC will be RM120 . No installation provide. Better DIY or get your reliable foreman do help you. There are some guideline.



If you ask "Any recommendation" over EDGE creator's sale page .. the only answer you will get is "Go for BT 502" which is RM1420 

for me I'll recommend you to set target at BT 303 (RM860) if you seriously need more on performance. Still you can try on Edge Entry Level, 2nd hand value very high all EDGE product. No worry when u plan for upgrade. U need to have faith on this product 1st 

What I can tell is .. got Waja manual owner happy with Edge Entry Level Always hit 7000 RPM over gear 2 .. easily

You can have a try. I offer you 2 weeks money back for the VS if you feel no improve. 1 condition, u need to drive your car to run in the VS. At least more than 10 hours.

the improvement of performance not like 50% of power / 50% of audio .. its all depend on your car condition 

oh ... Waja is campro oh .. so .. please settle your GC 1st