Sprinters and athletes that depend on those fast twitch muscles typically have extremely good strength to weight ratios. You don't want to worry about mass as much as you should be worrying about strength if you want to be fast. Now, you obviously need some very strong muscle regardless, so try to make the end result look more like the pro sprinters instead of the pro bodybuilders if that makes sense.
Plyometrics help increase your power and they're used for virtually every sport for this reason. With more power you can use more force to push off the ground in a shorter amount of time, which makes you faster. I read a book about the whole science of this but that's basically what you need to know haha. The shorter amount of time part is key though. Bodybuilders and powerlifters can definitely generate plenty of force, probably more than most sprinters when it comes to something like leg strength. The drawbacks to the bodybuilders/powerlifters is that they can't activate their muscles nearly as fast as the pro sprintes, and even if they can they have to haul around a lot more weight so they're still not nearly as fast (although they can be quite fast compared to the average joe).
Just focus on getting as strong as possible while staying very lean and keep doing the sprint work. Your speed will come. Everything the guys are saying about starting slow is a good idea too. Injuries suck and they can take you out of your routine for months, you don't want that haha.