Most people will say not to bother with the intake set up,for 200$+ and nothing really to show for any difference in performance but engine sound would do this only after every thing else is done that u want on ur outback, tires and rims depending apoun what u wanted to do more off road or less same with the subspention as well lower or higher number of spacers have been made I have sublet 1in in mine this was before primitive came out with the bit bigger ones, if u want to lower it,go with legacy parts,some one on this form has dropped their outback looks sharp, also 90% of outback owners of theses years added the sti rsb I don't know if 13s need this done or not but there is a line of front and rear sway bars from white line and others. anything that is legacy u can add from this as well, I have a good amount of bracing done to mine,vary windy in Vegas so adding what I did helped ALOT with the vary gusty winds we have almost to where I don't feel any wind no matter how hard it pushes gt spec is also a good one to go with if u want tower supports they have a stealth rsb that sits under the back mat so no one ever sees it and never know it was there at all
Rim sizes the lowest u can go is 16 unless u get a smaller brake kit that primitive makes for their new style wrx and sits that will fit on an outback if u wanted 15s
I have yet to see anyone add 20+ rims to the outback of these years but I am sure it can be done. 18s is as big as I would go
You can add a unequal length heard as well if u can get ahold of a newer style sti or wrx heard and do 90o outlet turn but this will not add anything to performance even might hurt it if u have the Pzev system
Best engine upgrade is just motor swap a sti motor and go from their but good luck with this
