lets talk "hypothetical's" here. this can be achieved many ways. All options assume the safest HP goal in each category.
(ie no 350HP miracle builds with stock engines)
Every 4efte is over 25 to 30 years old. pushing them beyond reasonable limits will quickly kill them. Try to think of what every owner does to a FWD Toyota starlet engine. Excessive Burnouts, clutch dumps etc.
rough costs are estimates, based on my country and history, You could do it cheaper if you know a guy, IE matt berry on Youtube.
One of the few who could legitimately do it cheaper And faster.
All sections assume a stock car, instead of progressive upgrades. All options are engine only, brake upgrades etc are a seperate category.
For Approximate labor costs add 25% to #1 and 50% to #2. beyond that i cant say. its per car, per shop.
#1 Stock everything, Cheap and nasty. Applies to EP91 4efe as well ( with turbo / manifold from ebay or 4efte Oem gear )
more boost, fuel cut defender, rising rate fuel pressure Reg.
Final result? turbo out of puff very easily At anywhere near 20psi, very inefficient, Maximum Fun. lower overall cost, But larger cost to grow further, Easily obtaining 170 odd HP on a 4efte. Very un-proffessional. Results on N/a 4efe Vary Alot.
Approx Cost for me in australian $ for this, using new parts only, roughly 2k$ to 3500$, labor is extra.
#2
the normal way,
Standalone ECU upgrade ( e-manage blue/ultimate ), Injectors from another car at 450+cc 255/lph Fuel pump and optional CT12 / CT9 hybrid OR TD04, Inter-cooler Upgrade from stock to Front mount, Civic Half Rad, New coolant pipes and thermostat.
Results, usually around 210Hp, more can be had, but also assuming the engine is not forged yet With a safer tune.
Approx cost, in Aud, assuming everything was new, and plug and play, 4500$ to 5500$ roughly. Not including shipping GST/tax/vat And labor.
#3 the expensive. If your wallet has not got a hole in it before this, it will after it.
Haltech Elite Ecu swap, new wiring everywhere, new Dash, Larger VF34/37/39 Turbo OR similar GT-3076 Garret turbo.
Externally Waste-gated, WEPR manifold setup,
Completely Forged engine + Gasket Rebuild, Larger more efficient Inter-cooler Upgrade .
**Engine break in Required**
( upgrades required, 255/lph Fuel pump Minimum, larger injectors again at 500Cc to 1000Cc+)
depending on manifold and turbo chosen, HP can be between 250 to 500+ Hp. Add an extra 1200$ aud for a tune.
(Gearbox Will explode at anywhere near 300hp. some people get lucky with higher)
( this is also way too much power for anything but semi slick Track tyres)
Cost of this is 20k+ and more if you run into any issues,
i ran into 1.2 years of issues with My #3 Build, resulting in the Final Cost Equaling 44 Thousand Australian $.
that was including, Shop labor And shipping of parts, but does not include The cost of emotional Damage, Depression, sourcing my own parts, and making things on my own time. Also Time lost Due to Professional Shop negligence Cannot be regained.
#4 Drag Build. Everything From #3, But with a Built Gearbox. And Add Drag Slicks.
not bothering with cost. pursue at own risk.