Pretty much what Vanflipx 1000 said . Leave the 4 lug for now and get the suspension and coilover work done first . The brakes are interchangeable between both 4 and 5 , so that upgrade can carry over between . As far as the S 15 Helical , there ' s OEM VLSD options that perform fairly well and can be had on the cheap which saves money for other build part options . Then go Clutched LSD and 5 Lug swap when you decide on new 5 Lug wheels . I ' d also look at a Cometic Head Gasket , ARP Studs and new Valve Stem Seals before adding boost pressure . Once you add the turbo , you ' ll need adjustments for airfuel levels as well , so I ' d look at injectorsfuel pumpFPR as well as a quality boost controller . This will keep you from blowing the KA a month after it ' s back on the road . With all of that said , I hope you plan to do this work yourself . With the upgrades you ' ve listed , as well as what myself and Vanflipx 1000 have suggested . you ' re already $ 2500 ish minimum deep , and that ' s a fairly generous estimate . If you plan to pay a shop to do this work then I usually suggest factoring in an equal , dollar for dollar parts cost to labor cost . You ' re on a good track though with the plan so far and I do wish you all the best luck in your build . It sounds like you have a VERY good canvas to work with and in the end will have a very capable and fun car !