Cosmo 13B-RE engine $1,500 Prices vary, but on average they range between $1,000 - $2,000.
Engine mounts $250 FC3S.Org offers their Cosmo engine mounts for $250. K2RD offers their Cosmo engine mounts for $450.
Flywheel {$400} Typical price for lightened steel or aluminum flywheel. Counterweight should come with engine. A used Kouki FC3S or FD3S stock flywheel should be priced under $100.
Clutch kit $350 ACT Heavy Duty clutch is only good for ~450lb-ft of torque.
Downpipe $100 Whether you're going single turbo or stock twin turbos, this custom exhaust pipe is needed to mate with the rest of the exhaust system.
Front-mount intercooler $1,200 The GReddy V-spec front-mount intercooler kit is the standard for which all front-mount intercoolers are judges for the FC3S.
Walbro upgrade fuel pump $150 Recommended.
Oil cooler lines $200 Typical cost to custom fab a pair of oil cooler lines from any name brand SS AN manufacturer (i.e. Earls, Russells, XRP).
Exhaust system {$800} This might be optional. If you already have a (larger) aftermarket exhaust system, this might not be necessary. $500 average for a good "cat back" exhaust, and $300 added for a pre-silencer section to be made.
Upgrade radiator {$500} Optional, but recommended.
HKS turbo exhaust manifold {$300} Optional, but if you're going single turbo, this is your cheapest option.
Turbo {$1,500} Optional - see above. Price is from Turbonetics.
Oil/water lines (for turbo) {$200} Optional - require for single turbo. Includes prices for SS AN lines and fittings for both oil and water lines for turbo CHRA.
Intake pipe (for turbo) {$100} Optional - required for single turbo. Piping and silicone hoses to adapt single turbo to intercooler and for intake going into the turbo itself.
FC3S water pump + housing {$300} Optional
Haltech E6X {$1,500} Optional - highly recommended for single turbo.
Minimally, you're looking at around $4,000 for this project.
With a single turbo upgrade, the project starts to edge towards $10,000.
Prices are typical retail, so it's possible to find lower prices.

20B engine $4,000 Prices vary, but on average they range between $3,000 - $4,500.
Engine mounts $250 FC3S.Org Cosmo engine mounts for $250.
Flywheel $400 Typical price for lightened steel or aluminum flywheel. Counterweight should come with engine.
Clutch kit $350 ACT Heavy Duty clutch is only good for ~450lb-ft of torque. A mildly modded 20B can easily surpass that.
Turbo exhaust manifold {$700} Optional, but if you're going single turbo, you need to have this custom made.
Turbo, T72 {$1,500} Optional - see above. Price is from Turbonetics. This turbo is good for 600 to the wheels.
Oil/water lines (for turbo) {$200} Optional - see above. Includes prices for SS AN lines and fittings for both oil and water lines for turbo CHRA.
Intake pipe (for turbo) {$100} Optional - see above. Piping and silicone hoses to adapt single turbo to intercooler and for intake going into the turbo itself.
Downpipe $100 Whether you're going single turbo or stock twin turbos, this exhaust pipe is needed to mate with the rest of the exhaust system.
Exhaust system {$800} This might be optional. If you already have a (larger) aftermarket exhaust system, this might not be necessary. $500 average for a good "cat back" exhaust, and $300 added for a pre-silencer section to be made.
Front-mount intercooler $1,200 The GReddy V-spec front-mount intercooler kit is the standard for which all front-mount intercoolers are judges for the FC3S.
Oil cooler lines $200 Typical cost to custom fab a pair of oil cooler lines from any name brand SS AN manufacturer (i.e. Earls, Russells, XRP).
Upgrade radiator $500 Cost of an upgrade radiator and custom radiator hoses to fit the 20B inlet/outlets.
FC3S water pump + housing {$300} Optional - if you can get the 20B water pump system, good for you. If not, we would normally replace the water pump housing and water pump with the stock FC3S units, easily available in the U.S.
MSD coils {$200} Optional - the cheapest option for 6 coils are $35/each from Summit Racing. You can find 3 pairs of FC leadings or 6 individual trailing coils.
MSD DIS-4 {$700} Optional - we would normally run a pair of these to use a "ignitors" in a Haltech install.
Bosch upgrade fuel pump $200 You can use a pair of Walbro 255lph fuel pumps for a little cheaper.
SS fuel lines and fittings $500 -6AN minimum diameter from gas tank to the engine. Includes all fittings to convert to parallel fuel rail system with aftermarket FPR.
SX FPR $200 Required to control fuel rail pressure
Fuel filters $100 You'd be crazy to not run fuel filters. Earls offers a pre-filter and a finer/regular fuel filter at $40/each at Summit Racing.
Haltech E11 $2,000 We recommend Haltechs for all our customers.
Front anti-sway bar $500 We can supply you the front bar if needed.
Just on those estimations, we're looking at a cost of around $10,000 without any of the optional components.
The optional stuff comes out to another $4,500.
Grand total for all components listed would be almost to an even $15,000.
Prices are typical retail, so it's possible to get most of it discounted slightly.