just trying to gain some knowledge on these scoobs really like them. anyway to the point can someone please give a decent but some what simple explanation of the differentials (front, centre (DCCD) & rear) set up in an STi and whats the major difference between these and the Evo's....yes the EVo has an ACD + AYC but what does this all mean.

Also what is the major benefit of retaining the stock dump valve as opposed to an after market BOV from say HKS? does the BOV really put u at a disadvantage as i read here that it causes the car to run rich? i have heard cars with 'woosh' sound and it didnt seem to be emitting any major black smoke but i guess the driver would best know as he has the guage to tell. do the dump vavles (whats the major diff. between the 2) give the same 'woosh' sound or is it to a less extent....i drove a JDM WRX ver. 7 and i dont recall hearing a 'woosh' sound maybe the engine noise defeated me hearing, my windows were down so no sound deadening devices in place to stop me from hearing it? yes so please answer my questions in detail

 

Some light reading about DCCD to star with: http://bbs.scoobynet.co.uk/showthrea...highlight=dccd

There are 2 types of dump valve.
There is a re-circulating DV that returns the air to the inlet path or the Vent to atmosphere (VTA) type that just vents the air from the turbo out under the bonnet(atmosphere).
The 'woosh' is from the VTA type DV. These have been known to cause problems with idle and rich running, but many people run them without issues.
Generally all turbo cars come with a re-circ DV as standard.

I take it the STI7 you drove had a std or uprated re-circ DV. In that case you are unlikely to hear it. Though they can be hurd venting into the inlet path through some induction kits.
DV's do not give better performance, though it can improve the turbo spool time on each gear change due to the lack of blade stall in the compressor side of the turbo.

 

thanks much appreciated