Power
ECU flash tune
+20–35whp est.
Easy$600–$80030–60 min
Home › Honda Civic Si
Honda Civic Si mods
Turbo engines respond strongly to a tune, so that's usually the first move.
Your Civic Si
Pick your year so we only show parts that fit your car.
Engine 1.5L turbo 4-cylinder
Stock ~205 hp
Weight ~2,900 lb
10th gen 2017–2020
Power
Cold air intake
+3–8whp est. · Best with a tune
Easy$400–$4501 hr
Power
Downpipe
+10–20whp est. · Best with a tune
Hard$850–$1,0003–4 hrs
⚠ Only buy a catted downpipe for street use. PRL says its catted version needs no tune, but most of the power gain comes with a matching tune.
+0–5whp est. · Keeps power consistent
Medium$650–$8003–4 hrs
Handling
Rear motor mount
Less engine movement
Easy$35–$1901 hr
Handling
Lowering springs
Stance + handling
Hard$350–$4004–6 hrs
⚠ Front struts need a spring compressor, which can be dangerous if used wrong. Many people have a shop do the front.
Handling
Rear sway bar
Less understeer
Medium$250–$3001–2 hrs
Brakes
Brake pads + fluid
Stops better
Medium$120–$2502–3 hrs
⚠ Brakes are safety-critical. If you've never done brakes, have someone experienced check your work.
Horsepower numbers are estimates at the wheels (whp) based on typical results. Real gains vary. Some exhaust and emissions mods aren't street-legal everywhere, so check your local rules.