Well… from my test on my spare wheels last night, it def is the best working cleaner i have used, I have used a few of the acid based cleaners, like meguiars hot rims, mothers FX, and the eagle one stuff, and none of them would do ANYTHING on the corners…
Heres some pics i took last night…
The offending corners on the stock 17" GTO wheels… A years worth of brakedust
Sprayed with P21S Gel, and allowed to sit for 2 minutes, Product says it can sit for up to 2 hours for heavy applications.
The first product to get those corners squeaky clean without me getting a qtip and getting to work 