G'day all, great to finally find a Liberty forum :-)

We have two Subies in the garage - an Impreza RS (MY08) and a Liberty Station wagon (MY08) - 2.5 non turbo :-(

My initial question is - whats the best way to get more get up and go ...not that the 2.5 lacks any, but just nice to have. Speaking to folks, the obvious bits are exhaust, air box and chip without cracking the motor open... Are these mods worth the $$$$ and who is the best person to do it through without voiding the Subaru Warranty ?