Most welcomed and my apology .. ARB = anti roll bars which stock cars has but common mod for large/stiffener ones due to the body roll with especially forester xt aka fxt owners.
Your positive experience with 2.5L forester is same as my experience with 2.0L version which we have in Singapore (no 2.5L) and it boils down to the suspension setup of the forester xt. Unlike outback and CRV or many other SUVs meant for road with no or little terrain capability, foresters are designed with terrain handling as well as road performance which is not easy and compromises are made, more so in the fxt since it had to been stiffened up to handle the glorious 350Nm 240+bhp else things can get out of control easily.
Sorry but no quick or inexpensive fix like just changing tyres on this ride comfort topic for the fxt but a lot of trials and errors with expenses as well as owners' expectation and sensitivity ... the wife of my forester friend made him sell off his fxt as she was car sicked too often which is already not an uncommon read. I would best describe stock fxt as a vehicle makes you feel like you are at 100kmhr when travelling at 70/80km/hr ... it is not a compliment and hence I asked and test drove many foresters with different suspension setups which fortunately owners here are often glad to help.
For me and my wife, pink springs with mentioned front/rear struts/arb, sti flexible system frame etc. works out fine ... great handling, no more floaty and jittery ride while still a bit higher frequency of of sedated bumps just like the new Merc E200 diesel taxi I boarded few days ago except the bumps of the Merc were less sedate.
Indeed the dueller sucks big time especially down concrete ramps of tight multi-storey carparks we have here ... not safe again for road performance of the spirited kind but should be ok for terrain and less sedate driving but watch the wet roads !
I installed the STI 20mm RSB/arb to control the body roll/boaty feeling. The car does feel more planted with that installed. However, that might have exagerated the bumps from the rear and make the car jitter more. However, it is a trade-off I'm willing to take.
I see. I will look get springs when the car ages abit more. the sti pink is roughly $500 purchased and shipped compared to mann $340. I would most likely go with Mann for economy purpose.