I have the ATP 2554 kit. Other power mods are 2jr DP (no cat) to Cobb CBE with cutout, Levels intercooler, Injen intake.
The shop that I go to have a 'heartbreaker dyno', it is true wheel HP with no corrections, hence lower numbers.
With the intake and factory tune, it put down 165WHP. With the intake and stage 1 OTS tune, it put down 171WHP with a bump in low end torque.
After running around stage 3 with a e-tune (no dyno), I wanted more power. Ended up going with a full recirc system with the install instead of the usual bigass TiAL BOV.
The two dynoruns are a year apart, but the air temp and humidy were within 4F/% of each other. If factory numbers are correct, 165whp/197crankhp=0.837 for drive train loss of 16.3%. If those numbers stay correct, 241.9WHP x 1.163= 281 crank HP.
In the interest of full disclosure, the factory dyno pull was on the standard 205/40/17, the big(ger) turbo tires were 205/45/17 RE 71s.
It was dyno tuned have it set to 25 of air lbs/min 19PSI. Looking at the compressor map, this puts it in the tail end of a 68% efficiency table at a pressure ratio of 2.25. For my car and altitude (14.4psi), it would have done no good for me too run 20-plus pounds of boost. The HPFP is running about 90% duty cycle. My tuner said he could get close to 255WHP, but I value reliability over 10-15 more WHP. The Levels intercooler keeps up with new turbo without a hitch despite what others might say (glancing during autocross, it is about 15F above amb.) It a nut shell, less power below 3K, but it comes alive above 3K. The 2554 will spool to about 7PSI below 3k and goes up rapidly from there. This is mainly an autocross car and I have not problem with the lower power below 3K. It actually helps that I'm not spinning the tires with a buttload of low end torque like the factory turbo. I have yet to take it to the 1/4, but it pulls on my friends factory Focus ST very well...
Out the door, (ATP kit, install and dyno tune) I paid <$3000. I could have saved on install by DIYing it, but having a baby on the way and just buying new house means I'd rather spend the money than invest the time.
And my favorite shoot for the 2015 autox season:
edit: added correct lbs/min figure