Suspension Polybush Kits include all the bushes required to convert a pair of front axle wishbones.
Uprated polyurethane bushes offer superior performance & longevity over the standard OE rubber bush. They prevent unwanted lateral movement of the suspension control arm to keep the car's loaded (dynamic) geometry/alignment closer to the ideal (static) value; this improves the steering response, braking stability and cornering as well as being easier on the tyres.
These polyurethane bushes won't degrade or soften like the OE rubbers and their firmer compound will stop your wheels from folding under the chassis when you try to lean on them - maintaining a greater and more consistent dynamic camber & castor angle to improve the front end grip and feel of the car.
I recommend upgrading the bushes as a matter of course when fitting wider wheels to account for the increased loads through the suspension.
There are 3 options available:
Fast Road spec
Features Powerflex's traditional purple firm PU compound. It outperforms the standard bushes and improves handling whilst retaining a high level of compliance and comfort on the road.
Competition A spec - 80/95a
This kit offers the support of a harder 95a leading bush with the compliance of a firm 80a trailing bush to give a looser, more intuitive cornering feel on some setups than the B-spec kit might allow - particularly with stiff list 1B tyres like the NS-2R. This is the specification of choice in the BRSCC Cup cars.
Competition B spec - 95a
Featuring the hardest 95a compound bushes all round to maintain the most stable geometry at the expense of some compliance. This is the specification I use on our own sprint car and I find it plenty intuitive on both the road and the track!