Jeff
at best the hp increase for a cai and cat back exhaust maybe 20-25hp gain. the WRX would easily beat the dodge off the line...as far as top end not sure. The WRX probably has about 300 hp and the dodge is 380hp but with the boost the wrx has probably not...

I <3 my Suby.
It sort of depends on a couple things. First the STI must be running an upgraded turbo if he's pushing 24psi. Anything over 20psi on the stock turbo is just blowing hot air and would not make any more power. If it's modified correctly, the STI should be making enough to run very lo 12's in the 1/4 mile easily which would be hard for the Dodge to come close to. But in the end it depends on the drivers.

Sean
I partially agree with I <3 My Suby, but there's a couple things he didn't know (no fault to him, he's brilliant with Subaru's, but I haven't seen him post anywhere else, IE the dodge section). I agree 100% that an STi with 24psi going through it would require an upgraded turbocharger, as the stock turbo would only make that boost up to like, 3500rpm, after that it would drop. However, it wouldn't be a drivers race by any stretch of the imagination, as a stock STi (at I think 14.5psi boost) has a stock Charger R/T covered by a full second. A stock 04-07 STi with a halfway competent driver can pull a 13.5 in the 1/4, and the best I've ever heard of from the 4100lb 370hp charger was a 14.1, and a cold air intake, no matter which one, and an exhaust, aren't going to give anywhere near an 80hp gain. Exhaust systems in the 60s weren't that restrictive even. The absolute MOST he could see is maybe 18-20hp, but that's unlikely without headers or a tune. So, a stock STi would beat him, and a modified one wouldn't waste their time. Your buddy just has a big ego and hasn't ran across an EVO, STi, or any cobra made in the last 15 years. Even an 05+ mustang GT would beat him, and the 99-04 GTs would give him a very good run, and they only have 260hp.

designergenes
You've already got some good answers. I'll supply the exact numbers. I give nothing to the cold intake -- a few who-cares HP at best. I don't know about the cat back, but I'm guessing it's less than 80 HP -- possibly a lot less. That said, I'll pick a 2010 Subaru STI, because you didn't say what year (It makes almost no difference anyway). The cars: 2007 Dodge Charger R/T: 5.7 L V8, 340 HP, 390 lb-ft torque, 5 speed auto tranny, 4289 lbs 2010 Subaru STI: 2.5 L H4, 305 HP, 290 lb-ft torque, 6 speed manual, 3395 lbs The math: Dodge = 12.61 lbs/HP Subie = 11.13 lbs/HP Clearly the obese Dodge is in trouble from a dead start. While the Dodge's lockup torque converter helps, it doesn't help as much as the Subie's AWD does, starting from zero. The Dodge has 34% more torque, but weighs (894 pounds!) 26% more than the Subaru. That's about a draw. The Subaru is faster off the line, especially if the Dodge driver uses too much foot and 'burns' the two (2) rear tires. Let's assume about 125 mph as the 1/4 mile is hit. The Subaru is in 4th (or 5th?) gear and the Dodge is probably in 5th (top). The Subie has an advantage here too. Way down the straight pavement the Dodge might catch the Subie, but it's going to take miles, if it ever happens. On a road course the STI will eat the huge, top-heavy Dodge alive. Subaru all the way. The truth is, the Dodge "muscle car" hasn't enough muscle to really haul its weight. There are all sorts of cars on the road that can beat either of these. How about a Porsche GT2 RS at 3,150 pounds with 620 HP? A Corvette ZR1 at 3,333 pounds and 638 HP? The 2011 AWD Porsche Turbo S (530 HP, 7 speed auto, PDK, tranny) hits 60 mph in 3.1 seconds, easily beating the ZR1's 3.4 seconds, and making the Dodge and Subie look like they're standing still.

Jason
Subaru all the way. I'm with designergenes all the way on this on power to weight ratios, and he or she did not even factor in the huge gain that 24lbs of boost should give. You would probably get answers of Dodge more in the Dodge, section and Subaru more in the Subaru section of Yahoo Answers, but I really have to say heavy boosted lighter weight STI would walk away from the RT with a cold air kit, given both had decent drivers. And that is only down a staight line of open road. Put some curves or wet roads in there and it would be a joke. And I like both of those cars just fine.