Did the guy lower the front as well as the rear ?/
The purpose for raising/lowering is to un-weight/weight and/or remove/add turning and braking in corners , as well as alter high speed stability (head shake) , i did not lower my 450X internally (though i did personally re-valve both my bikes), i did the lowering with a Kouba Link , and moved the forks UP in the clamps to 6mm , my 02 450R is recommended to be set that way stock and is where i have it as well , so its a common practice to alter steering and "feel" of the ride
The reason Honda has them higher is to give the bike a more neutral feel , though most people tend to alter this setting because most feel Honda's do not have enough steering in corners and tend to push , the exception is the 09+ 450R that everyone complained about a Stinkbug feel (the rear too high) , but that was due to too soft fork springs
So basically , if you set it at 6mm for example (where i run both my bikes) , you will get improved steering into corners and still retain high speed stability , if you notice you have a lot of front end push in corners , or the front end just deflects a lot off rocks/roots , etc , then raising the forks will take some of that away, and make the front feel more planted
If the bike is knifing (turning too sharp making you almost crash because the front end turns so sharp you almost get thrown off the bike )in corners (dont confuse this with front end push/wash outs) then lowering the forks in the clamps (making them flush with the top clamp) will help
The key is to balance the bike front to rear , giving sharp enough turning to remove push , but not to make the bike knife or feel like your going downhill while on level ground or taking away traction from the rear by putting too much weight forward , also make sure your sag is set correctly before worrying about the front , if the sag is not right , the forks wont be right no matter what you do , its a balance between front and rear
I would suggest trying it like it is and ride for a bit , then raise it 4mm and ride it a bit , then change it to 6mm , you should feel the difference , try riding for 5-10 minutes with each setting at the same location to get a overall feel for each position , then decide what you prefer , there is no right or wrong in this and you can go anywhere in between , , its all about how the bike reacts and how you like or dislike the reaction
IMPORTANT NOTE:
When changing the clamp position , do this with the bike on the stand AND (very important) with the front wheel OFF , when you set 1 fork where you want it (say 6mm) then put the other fork at the same measurement but only slightly snug that side , now stick your axle thru and see if it slides all the way in without force of any kind (spray WD-40 on the axle and wipe it down to assure its free from dirt ,etc that can make it stick)
If the axle hits and you have to slightly raise or lower it to get it in all the way , then move the loose fork up/down to allow the axle to slide in smoothly and freely ,(you may only need to move it 1/16th of a inch or less to make a difference) then torque everything down , re-check the axle is smooth in and out , then replace your wheel , this is a must for proper suspension movement , most people overlook this step and think there is a issue with the suspension , and it was only missing this step when making physical changes to the fork tubes themselves within the clamps
Sorry for the book , but hopefully that helped explain it thoroughly enough to give you a place to start with your settings !