I would also personally not cut the rears either as the PCA kit only comes with shorter front stops and when speaking to Peter he has told me the rears must remain long, his actual response when I asked if I needed shorter rear stops:

No the rear bump stop must remain long. It's required to support the rear spring when carrying extra load and maintain the handling balance of the car. A short rear bump stop would make it understeer more as you build the lateral acceleration in a corner.

 

Modrich is using twin-tube dampers front and rear - 22mm rod.
The front 50mm (40mm +10mm soft nose) bump stop, that comes with the pca spring set, is for inverted dampers - 12mm rod.

Modrich is already using the 90mm, rear, twin-tube stop. Which, as he knows, doesn't need to be shortened, with the pca wrx springs, for the reasons Peter gave you.
If the rear springs lowered by 15-20mm the I would remove the smallest section. Making the stop 75mm long. Or, as I have done on the classic spring sets, find an alternative rear stop.

 

The front twin-tube 60mm stop is so soft, and progressive, that I don't think it's an issue. I would hope you've got at least 20mm gap between the stop and the platform?

Having seen Plenty's image of his 60mm stops, they've obviously been working hard and split. It would be interesting to know how old they are.

You could cut the smallest segment off the 60mm stop, giving a 42mm stop.
Slide a tube of protective metal (snip up a drink can) around the 22mm rod and into the bump stop - then get slicing with the bread knife. Rotate the stop, to stay in the best cutting position.
Or better, change to the optimal/febi stop: As, by cutting the oem stop, your diminishing the solid height.

On balance, If you've got 20mm clearance and the stop's nose hasn't split, I'd leave as is.

You don't need to shorten the dust boots.

HTH

 

Ahh thanks for clarifying things 2pot

Installed my rear non inverted struts today, knocking be gone! Such a better design.

 

Thanks for clearing that up 2pot, I'll take a look when I get a chance and decide what's best to do

 

To clarify - I obtained a used set of OEM front WRX bump stops along with used Prodrive Red 05+ STi springs and new twin-tube KYB AGX dampers, to replace the suspension on my STi. I do not know how old the used WRX stops are.

At the time I didn't realise that the Febi/Optimal items existed otherwise would have ordered these instead.

I am finding the Prodrive/AGX/WRX bump stop setup too stiff for my requirements, so have ordered a set of Febi bump stops to be fitted to the front in the hope that this will introduce more compliance.

 

I thought I would update this thread a bit, so after running the rear KYB none inverted struts for a while I decided to change the fronts too, to have a matching set of brand new non inverted KYB shocks with Prodrive spec springs.

I can confirm those Optimal bump stops work great! So thank you very much 2pot for the info.

The dust boots from the inverted struts seem to work with these too.

 

Anyone got an old rear blob/hawk top mount, with old dust boot, that they don't want?
I don't need the bump stop.