It's definitely believeable. With my stage 2, I gained about 65 hp. I attribute 25 to the exhaust and the rest to the unichip.

 

I just installed a TXS-stealth back exhaust bolted to the stock muffler. Took about three hours to remove old and install new system on jack stands. Exhaust tone still sounds stock, but I can really hear the turbo screaming now. Is this from the downpipe or the removal of the upper heat shield? I know I don't feel 26.5 WHP, how much is the stock muffler holding me back? Hoping to get to VMSP on March 10th to run the 1/4. Considering TXS, Prodrive, or Buschur Racing axle-back exhaust, like them all for different reasons. Want a deep tone but not loud.

 

Forcefed,
Give the car a bit of time to relearn with the new exhaust. Also, and I may be wrong, I think the 20+ whp gain attributable to the turbo back is what is gained with a ECU upgrade to accompany it. I can't see getting that much power without it...
I highly recommend the Prodrive muffler section, that's what I have. It's a tad quiter and mellower than the TXS unit, but that one still is very reasonable in sound. I love the oval tip of the prodrive though, rather than the grapefruit shooter look of the STi.

 

Ezatnova TXS is claiming 26.5 WHP with just the exhaust, 59.4 WHP with UTEC and exhaust, and 35 WHP with just the UTEC. This also included having the resonator box removed. I was going to do a ECU reset but didn't, I think I've read three different ways to reset. How long will it take to learn naturally, it's been a week. I really don't run the car that hard, rarly above 7 psi on daily commutes. Is most of my power gain at the top end? Thanks for the advice on the axle-back. I'm just going to drop the axle back section when I run at the track.

 

You're going to be much better off jsut doing a reset than waiting and wondering. It takes 5 minutes max, so just do it. Unplug the negative terminal, press the brake pedal, reconnect and go. The biggest PITA is reprogramming the radio stations and the clock
The car will feel like crap for a few miles, but will get better rapidly, although it was more drastic for me since I has the unichip too. You should bea tth ecar pretty hard when you are relearning the ecu. wind it out and get ito some boost.

 

Yeah, I did a reset after I removed the intake silencer. Stomped the throttle, taking it to redline in 1st, 2nd, and third gear and hitting max. psi., did this a number of times plus drove it overall harder than normal, sound good? Looking to drop in the TXS UTEC next, they are claiming 227.8 whp with this set up, how much is the stock muffler restricting me?

 

well. at the point that you have the utec and a turboback, the stock muffler starts to hurt a tad. Not awful though, but you can probably pick up 5-7 with a good unit.
Let me put it this way, with my stage 2 (unichip) with the prodrive unit and cold air mod, I got dyno numbers of 250 hp and 240 tq to the wheels.