Question
 

how many hacks can you add on to the Vbulletin? is there a limit?

6 or php will blow up. ^^

j/k, there is no limit, though the more you add the more queries it takes to exacute and that could be more load time on your site and or server. But i have around 12-15 can't remember really. You'll be fine.

There is no actual limit of modifications you can install.

Be advised though, that the more modifications you install, the more probable it is that:
- one conflicts with another
- you loose performance due to all the additional queries
- it'll be much more work to upgrade when a new version of vBulletin is released

It's generally a good idea to just install those hacks that you find will benifit your community the most.

Thanks..