The turbo plumbing is all done in high-tech urethane tubing, there's a revised air-box and the waste-gate dumps externally, delivering a very satisfying spchsssh noise as it sprays its unwanted psis all over the engine bay. 

Luxon is convinced that a turbo installation these days will live or die on the quality of its intercooler.  So, the R-Version gets the biggest air-to-air job that would physically fit.  It's mounted down low at the front for better air flow and makes the lairy bonnet scoop superfluous. 
The exhaust system is the other integral part of the package and it's a big bore unit (but not stupidly big like some Rexes run).  The note sounds the business when you're giving it curry, but can get a bit drony on the freeway. 

The all-up result is about 148kW at the wheels (a good STi makes 125) and a torque curve with no holes, no valleys and no troughs. The car we drove was APS’ development car and boasted 17-inch Speedline wheels with Pirelli hoops.  More interesting was the front diff, a limited slip unit that makes the Rex turn into tight corners without the customary understeer. 

Around town, it makes the steering load up a bit and it chatters during U-turns.  But for the type of club racer of hillclimber at whom the R-Version package is unashamedly aimed, the slippery front diff will be good news and, although it now costs extra, it'll be popular. 

Bottom line time? Okay, the R-Version is an amazing piece of gear.  It takes all of the guesswork out of fast take-offs and makes gear changes less time consuming. 

It's also a bargain. Perhaps most significantly, it'll kick an STi’s bum good and proper.