you can do the work yourself and deliver the car to an engineer, but some of the items are not that simple, belts are not required if there in good nick, but must be retractable in the rear, which silvia usually doesnt have, tyres are ok if they are roadworthy.
but intrusion bars are a pain, if u attempt them, make sure you speak to your engineer as they all have different requirements for dimensions and the way they are fixed, fuel filler restrictor is also a pain if you dont have the correct tool, r32 filler necks are a pain.
we charge $1300 for r32 and $1500 for silvia(silvia requires rear belts)
Dean