i can relate my experiences on using dynotab.
i brought in bulk online thinking i be wise on saving through bulk puchase as i have 3 cars to be used on.

initially it feels great, engines sound smoother and there is fuel saving of between 10-20% on my 3 cars.
but after a few tanks of fuel , problems started, all 3 cars have problems.
1. my volvo develops starting problem, hard to start (i.e. first start of the day)
2. my toyota develops increased fuel consumption
3. my kia started giving jerking problems when accelerating
after I stop using dynotab, all the above cars comes back to normal without ever going to a mechanic.

DYNOTAB USA practise return and refund policy if you are not happy with their products BUT DYNOTAB malaysia happily response to you when you enquire about purchasing , and not even a reply when you are not satisfied with their products.

my conclusion is , DYNOTAB will damange your engines, BEWARE.

if anyone is interested, I still have a lot of dynotabs and dynotab plus waiting to be returned for a refund(hopefully)

DO NOT USE DYNOTAB.

darmned right i m mad n hopping mad as well.
asked for refund but no dice, wrote to US office also no reply, this just shows that they do not stand by their products, just a scam for fools such as I