I am just wondering if anyone has installed an ECU chip in '91 CRX and how well it worked, is the horsepower increase as significant as they claim?

 

The only chip you should ever install is one specifically designed for your car, not just your model. The resistors that they sell as "chips" on ebay are crap and can really only do harm to your motor. Leave it alone or dish out the money for a Hondata, or similar unit, and get it on the dyno with a professional tuner.

 

As 213374U said, dont mess with those ebay chips the are junk, stick with the basis for easy hp, get that motor to breath better with intake, exhaust and ignition

 

google crome for obd1 ecus. you may consider converting to obd1 and using it in the future. if you want you car to be faster then you might want a engine swap or a turbo kit. either way you will need engine management. ( like crome, ectune or hondata)

 

i have installed the D16Z6 head and converted my CRX to OBD1 like Bnuts mentioned above. That way you can use a P28 ECU which has many available options for tuning. Even with stock maps, the car pulls harder, runs smoother, and gets way better MPG.