Well written RobEvo5.
That' is an excellent write up and spot on.
SCOTTIE. Rob's post does sum up the difference very well. I have driven my mates 2.5 (running at 400 ish) new age flat through the gears and the response is virtually instant and was real good fun. (boost Im guessing at 2500rpm to 4500K
With mine (2.0) you retain the boost for a longer period. I boost at exactly 4K to 8K.
Rob & I have both been there, done it & got the fooking T-Shirt

and looking back you wanna stop at 400 Bhp. Great power to weight & you know you have a proper bloke toy.
I have a P1 and they are a fantastic base for modding. When all other guys reach 400 it's not long before weight becomes an issue if they intend to achieve 400+.
You won't in a P1 as they only weigh 1290Kg's.
(IF) you get bored with 400 & want more be prepared to start spending big money. To get from 400 to around 600 will cost you at least 4 times what it cost to achieve 400.
Also a thing that is often overlooked by many is a P1 is more Prodrive than Subaru. Most of the set up is Prodrive & their level of knowledge is right up the top end.
At the next meet I will take you for a spin using the LC and show you what a modded 2.0 P1 is like, if you wish?