SteamSpeed fully supports WRX (08-14) and Legacy GT (05-09) with the same excellently designed and tested turbos for the STI in an LGT stock-location fitment. This means you don't have to compromise with your turbo selection, and you can continue to use your other upgrades designed to work with the stock turbo like LGT-style flanged intercoolers.
How to Choose a Turbo
Which turbo is just a question of how much power do you want, and do you want or need a ball bearing center section.
Size Choice: for the LGT fitment, we have arrived at two ideal sizes: the 67+, and the 71. Both rock the same larger turbine wheel (TD06SL2) which has proven to be ideal for the EJ25 motor, so the difference is in the size of the compressor wheel and how much they flow or in other words how much power they can make. The 67+ is designed to make around 350-400 whp on pump gas, and ~20 psi; whereas, the 71 would make around 400-450 whp assuming supporting mods, and the turbo is the bottleneck.
We recommend the 67+ for people with a stock block and it produces safe power levels for stock blocks, ie. less than 400 whp.
The 71 really is the ideal turbo for the EJ25 found in WRXes and LGTs. It makes loads more torque and power everywhere across the powerband vs stock and doesn't fall off at high revs. But one problem is it makes stock-block breaking power levels, so we generally recommend it for either those with built blocks or those who want a larger turbo to grow into.
If you have a stock block and want to grow into the 71, it can be tuned to safe power levels by your tuner; for example, a 71 with a boost target of 15 psi could be tuned to less than 400 whp. Later on, when you have a stock block, it can be retuned to over 400 whp.
Bearing Choice: we offer our 67+ and 71 in either journal bearing (JB) or ball bearing (BB). In this application, the difference mostly comes down to price: JB is more economical, and BB is more expensive. Don't get us wrong, BB is better. It is more durable, handles high boost better, and is more responsive, especially on and off the boost. However, for average usage, JB will be about the same most of the time.
Also, we are super excited to have upgraded our entire LGT line to GEN2 BB. Lean more about SteamSpeed GEN2 Ball Bearing turbos.