Roldan bro, you've gotta come clean about it....you are driving you mom's car, launching it and generally driving like you stole it. And the car is tuned. You know what gave it away ? Your knowledge of the gearing ratios and the desire to put an STI tranny into it. If it was your mom's (and moms are unlikely to buy a manual car, regardless of how Euro born and raised they are), you'd be very happy to repair the OEM one because it is her car and you would not care for a better one.
I know people with approximately double the factory power still on the OEM spec gearbox...They are very reliable to about 300 whp (the general wisdom here on the site). You should look into your clutch|TOB options before you split the tranny and do your 2nd, 3rd and 4th synchros. And as far as the tranny swap threads...they are everywhere; there's even one or two stickies and/or Master Threads. And yeah...go elsewhere...$2500 is too expensive.