Tactrix cable and ecuflash and to raider is the easy way or ecuedit is another but you really need to have a good idea about tuning principles if you want to mod the map yourself, a good mapper is worth the money in my opinion, only reason I looked into it was that on my old wrx I fitted all ppp parts then flashed a ppp map to the car so was no different to paying the £1600 at the dealers just that it cost me less than £300 all in and was great, any custom tuning needs the knowledge, equipment and a fair bit of time to get it right where a mapper with Subaru experience will get the results much quicker