while I am not exactly sure the OTF (off the shelf)maps are for different stages but not necessarily different brands. I know I personally picked up over 50 hp/ft lbs back in the early days. to put in perspective I paid 1200 bucks for a turbo to net me 55hp and 15ft lbs if you can get that for 3 hrs tuning it is a mod in itself.
Depending on what Engine Management you decide on, there are several ways it can be tuned. With the Cobb AP, most common choice nowadays, you can buy the AP unit, and get free OTS (Off the Shelf) maps to load. The off the shelf maps are tuned based on the components you have on your car. For example, you can get an OTS map to compensate for an aftermarket exhaust. The Map is tuned to a generic level that should be an improvement for any Subaru with any exhaust. Then you can take it a step further, and get tuned by a professional like SS at Topspeed who will custom tune for your car. 2 06 WRXs with the exact same exhaust system will not react to the mod the exact same way. One car may get a little more HP than the other, so a custom protune will get you the most for your upgrades as it is custom tuned specifically to your car.
good info as I've always been curious as well. getting ss tune a week from tomorrow! can't wait to see the numbers!
Experience, for the most part. When you receive a protune from Scott or Doug here at TopSpeed. They have more experience in tuning your Subaru then you know. Together they have probably came close to tuning 2000 Subaru's in the last 4 years. Not to mention having the fastest Subaru in the country in Time Attack. They will get the most power out of your car safely.
Also tuned the world record holder amongst those too The off the shelf tunes are fattened up tunes that 'should' be safe for any car with the specified mods for that tune. A professional tune will dial in 'your' car. For instance, your car may like timing more than boost. My car may like boost more than timing. Therefore both are tuned differently. No two engines are identical. Each one has a different flaw (burr in the head, material diffs, tighter spec valves, etc). The professional tune is catered specifically to that one engine. Lets say you copy tit for tat every single mod on my car to yours. It wouldn't be wise to load my professional tune on your car because your car may not like the same things mine did. Engines are just like people.....they all have their own likes and dislikes and personalities.