I have a JDM B18C GSR in my 99 EX. For some odd reason it tends to back fire at times when i left up off the gas and step on it again. When I dynoed it a couple months ago I was told that it was running rich up top. Im also running the STOCK EX cat. Which can more than likely be my problem. Also do you think i can expect a larger gain by swaping out my EX cat for a high flow?.

 

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