At Acceleration we sell both OEM and aftermarket brake pads. The aftermarket and the OEM seem to be similar quality, but sometimes there is a difference in the compound. Make sure that you use the correct brake pads for rotors that aren’t steel, or you will ruin your rotors and pads.
Darren, For our OTK karts, we used EBC FA540S brake pads. I’d get them off of ebay from a Kart shop in the UK for $15-$20 a set; yes, a SET.
My Son raced Rotax Masters and won many National events with these from North Carolina to Sonoma.
He won’t use anything else.
Once a day I’d have to hit them with a file as they have a high metal content.
We used the Green “soft” pads even in the hottest temps and never had an issue.