Have your buddy check these out and see if these would convince him to hold onto his STi.
http://www.dpccars.com/car-movies/11...ti-Type-25.htm
https://www.evolutionm.net/forums/sh...d.php?t=236413
STi is a great car and doesn't take a lot to make it a fantastic car.
$5,000.00 would certainly help STi to handle as good as evo.
Proper coilovers, bushings, bumpsteer kit, and whiteline swaybars (especially 27mm rear bar) would transformed the handling of STi.
But, having said that I don't have any regrets with my decision to go with evo.

 

Lol I love how people say don't trade it in then say no regrets on purchasing evo. I have no regrets to, I struggle month by month and love it everytime I drive fronm work to home

 

If he really wants to get an Evo tell him to sell it privately so he wont take a huge loss.

 

I never felt like I had to ask anyone when I got my car. You shouldn't have to choose one or the other- it should just feel right.

 

keep the STi

 

I had a 2004 STi. Honestly wasn't all that impressed. It has been said the 04's were a bad example of the Sti. So now that I've had my MR for awhile, I went to my local Subaru dealer to test drive this 06' STi they had. I prefer the MR hands down in every way.
I am a pretty open minded person. For me, between looks, feel, sound, I prefer the Evo.

 

I just want to comment on the ease of modification... I wish it was as easy to mod my Evo here as it is to mod a Subaru... There aren't any shops around (yet) that can do extensive well qualified work on the Evo, there are lots of Evo fanatics who know a lot about the cars and have done much of their work themselves, as well as a few of those general car shops that can do a bit... But COBB is about a 10 minute drive from my house, if I bought an STi it would be MUCH easier to take care of and mod than my Evo... It's all about location, and driver, their time attack STi is mean, and the new 06s are certainly a force to be watched.

This is my advice: Tell him to keep whichever one he thinks looks better, that's the sole reason I picked the Evo over the STi (and no, it isn't the only difference, but it is a big one).

And from a racing perspective: A good set of tires and coilovers will make the STi plenty competition for Evos on the track, add Stage 1 or 2 and you'll be sitting just fine (and a lot less expensive than 5000 dollars in mods for sure), I drove a COBB Stage 2 06 Sti on the track (that's the one with the full TB exhaust and the tune, right? Stage 1 is just the tune, if I'm right) with all seasons on it and it was pretty nice, my only complaint (besides the obvious all season tire problem...) was that it needs some stiff coilovers but that's because I was used to mine, overall it handled great, and I was still faster in it than PLENTY of much more well prepared cars, and a few less prepared Evos (stock, or TBE only, but still with all-seasons on as well).