it looks like a stock pipe,but i could be wrong it (could be new stock exhaust), the oil and gear oil is fine, when i had my 4 stroke i used 10w-40 synthetic the gear oil is fine for both scooters, i think the A7TC is a cheap chinese plug the ngk should be much better, as far as the oil it is a little dark, i noticed when i used synthetic it would come out darker than regular oil
