Fastest to 300 wickets. He has slowed down a bit since then. Might find it difficult to keep that record going as Murali got to 400 wickets in 72 Tests and 500 in 87. I've seen a few discussions on whether he could get to Murali's 800. The problem is he's already 33. Murali was around 30 even when he got to 400 since he started playing for SL at a young age. Going past Kumble is a realistic target for Ashwin. He might play for another 6 years.