I can give you a valid answer for sure because I ran that intercooler untuned for a few weeks on my 06 STi.

Yes, it will totally throw of your tune and totally kill your performance. That is a big bump in volume and cooling.

For example, at the time I had a TBE, Cobb stage 2 reflash, and APS CAI. Then, I added the DR525.

WOW, ran pig-rich... like 20 MPG cruising and had MAJOR lag to where a hard launch was not possible. It also barfed fuel during hard shifts with lots of pops and burbles.

The good news is that a simple pro-tune will revive it.

Topspeed got a hold of the car 2 weeks later and fixed everything. Doug's exact words "it really threw off the tune," pertaining to the DR525.

Anyway, congratulations. That is a great intercooler and has suported over 500 WHP on my current tune. It is also well built, surviving 150 miles af hard Sebring track days and many Bradenton launches. After you get it tuned, the car will perform but expect more lag due to its larger core size. Also, heat soak will be non-existant.

Steve