It really depends on how you ride your bike as well. I wouldn't put anything with more travel than 120 mm so the bike handles properly. Do you bottom out the suspension often where you currently ride? If you only bottom out once or twice per ride, you're probably okay with the fork you have. Or are you looking to get into DH / Freeride? Whatever you do, just keep in mind what kind of riding your bike / frame was designed for. Like was mentioned a XC frame could easily break trying to land a big hit. If this happened, even the cost of a broken arm would be more than a DH or freeride bike. If I were you,as long as the stock fork is working for you, I'd save the money towards a dedicated DH bike.