If it aint broke, don't fix it. I have a good budget when it comes to mods, but I don't believe in spending money if (or when) I don't have to. Lets face it, few people ever keep their cars more than 5 years. If your motor has been well maintained and hasn't given you any problems, I wouldn't rebuild it if you're looking for up to 450 hp at the crank. I know guys that have 525+ hp in their tt's and never opened their engines up. And yes, reliably. A buddy of mine is a service advisor at a Nissan dealership and handles this guy.