[mwebb]

Originally Posted by greenfuelbooster

Restrict air after the MAF sensor. This will make the car think it is driving at high altitude. At high altitude there is less air. The ECU is forced to inject less fuel.

umm
no , your modification will not have any effect at all .

the MAF just counts the air , that's all , it can not measure pressure , directly , some systems like Ford s can use the MAF flow at WOT to CALCULATE BARO .

because VE is known and displacement is known and temperature is known and RPM is known .
pressure can be calculated .

feed back from the AFR sensor or 02 sensor will keep fuel trim and actual AFR right where the ECM wants it to be , to the limit of authority of the AFR sensor or 02 sensor .
==================================
so if flow is restricted , by your foot or by the plumbing , the result is the same
but
at WOT , your VE will suffer , strangled by the restriction.
altogether , not a good idea .
=====================================
why do you think it is a good idea ?
Does an 06 civic , your 06 civic even have a baro PID ? if yes , does the system arrive at the value using a MAP / Pressure / Baro sensor or a calculation ?
==========================
culled from the list of available PIDs for a 2006 Honda CRv

....
dding (22): All Injector Deactivation Mode
Adding (23): AT 'D' Position Switch
Adding (24): AT Neutral-Parking Switch
Adding (25): AT-CVT Reverse Position Switch Input Status
Adding (26): Barometric Air Pressure
Adding (27): Barometric Air Pressure - Volts
Adding (28): Battery Voltage
Adding (29): Block Learn For IG Timing Collection For Knocking Control
Adding (30): Block Learn For IG Timing Collection For Knocking Control EGR Condition
Adding (31): Brake Switch .....

we see a PID for Baro pressure and Baro sensor voltage , indicating that the value is measured by a pressure sensor , not calculated .

HHO is also a bad idea --------