Given the superb handling and balance of the Impreza WRX models, there's nothing particularly exotic about its suspension design. There are MacPherson struts all-round, with coil springs, transverse links and anti-roll bars at the front and back. Forged aluminium lower arms are used at the front, while the rear suspension has trailing arms to further locate the hubs.
The only real issue you will likely encounter with the suspension is a knocking sounds from 2005-on cars, which were fitted with an inverted KYB damper as standard. The inverted strut slowly loses oil and lubrication, hence the knocking. You can rebuild the original shocks, but the noise will come back, so best to replace them altogether with a set of KYB Excel Gs from the likes of Camskill. While replacing the dampers, you may have to renew the bump stops, which are becoming hard to source, so make sure you have these on order before starting work.
Eibach springs are a common upgrade for the WRX, especially cars used for track days, and were part of the Prodrive Performance Pack. The Eibach springs are very good, but they don't work so well with the standard dampers, so you need to budget for both when upgrading the suspension. A Whiteline anti-lift kit will help dial out understeer, but it is essential it's fitted in conjunction with a full alignment check to make sure the suspension is in perfect fettle.
Front and rear strut braces are another common addition. Make sure they are securely fitted and do not rub against any engine components.
Power assisted rack and pinion steering has 2.8 turns from lock to lock for the WRX and 2.6 turns for the STI, with many owners pointing out the steering can feel quite light at the wheel but you soon adjust to it. The WRX has a slightly wider turning circle to its predecessor, needing 11.0-metres to the Turbo 2000's 10.4-metres.
Braking is taken care of by ventilated discs front and rear, with ABS fitted to all models. The brake discs last well, but the calipers corrode and seize. While the calipers can be rebuilt, most owners simple replace the old pistons with stainless steel items from Godspeed for £120 a set. Braided brake hoses help with better feel and less fade, while uprated pads and fluid also help reduce brake fade. STI versions have larger front discs as standard and wider 225/45 R17 tyres in place of the WRX's 215/45 R17s.
Tyre choice has a big bearing on how the Impreza WRX will behave. Cheap tyres are fine for running around on and the car's inherent balance and traction will flatter these tyres, but to get the best from the car you need premium tyres. A set of decent ones will cost around £400, with many owners recommending Bridgestone RE050s for the WRX and RE070 for the STI.
Subaru fitted 16- and 17-inch alloy wheels to the WRX, and 17-inch alloys to the STI. They don't suffer from the porous problems of the earlier Turbo 2000's wheels, but check for kerbing. In 2005, Subaru changed the wheel stud pattern on the STI, which means you cannot swap wheels between this and other models.
"I should have upgraded the discs immediately I bought the car but didn't and it ended up costing me more in replacements. The standard discs are inadequate for fast road use and kill the fun a little as you end up being gentle with them to protect them."