STiMulated 
 
 
 
 
 

 

"On the road, it all means the APS STi is a more relaxing drive because you’re not constantly hunting back through the six-speed for a ratio that’s actually gonna spool up some herbs. The thing will actually accelerate in sixth now, which is really saying something."

Motor
Magazine 

 
 
 
 
  
 
The real clever bit is the Unichip piggy-back computer which incorporates boost control and therefore allows pretty finite control over what the turbo contributes and when.  While the stocker boost at about 17psi at 4000 rpm, tailing off to nearer 11 psi at 7000 rpm, the APS mods leave the boost as is at 4000 rpm, but squeeze it up to 13 psi at 7000 rpm.

That makes it a bit keener at full chat with power at the wheels lifting from 148 kW to nearer to 175 kW.

But what’s the most impressive is that the boost comes on earlier and gives a much fatter midrange as well as some much-needed urge off the bottom end.  It’s still ain’t going to win a tractor-pull competition, but at least you can give those prats in the Commodores a bit more of a challenge.

On the road, it all means the APS STi is a more relaxing drive because you’re not constantly hunting back through the six-speed for a ratio that’s actually gonna spool up some herbs. The thing will actually accelerate in sixth now, which is really saying something. 

There’s still precious little happening before the tach needle starts to swing a fair way north, but useful boost is happening a full 1000 rpm lower, even if it’s not the full boot up the date that chimes in at 4000 rpm.

There’s still the opportunity to get the shits when the light goes green, your boot goes to the floor and bugger all appears to be occurring.  The trick is that nothing doesn’t actually continue to happen for as long as it can in the factory STi. 

And since there’s more grunt happening earlier, you don’t feel quite so compelled to bury the gas pedal in the Axminster as a means of responding to the lag.  In fact, the superior part-throttle urge at any speed below 4000 rpm is probably the cleverest thing about the transformation.  Gaps in the traffic can now be filled without reaching for a big clogful and while that might not sound like a huge achievement, believe us, it is.