So I took my 2009 Nissan Altima for the yearly inspection and it failed the emissions test, something about high hydrocarbon readings. The car has been feeling sluggish lately too, especially when accelerating onto the highway, and the fuel economy has dropped by maybe 15 or 20 percent. No check engine light though which is weird because I thought a bad cat would throw a code. A mechanic did a quick check and said the exhaust backpressure seems a bit high and he suspects the catalytic converter might be partially clogged after all these years and kilometers. He quoted me a huge amount for an OEM replacement but mentioned there are aftermarket options that are much cheaper as long as they meet local standards. I’ve been looking for a place that can supply a superior catalytic converter abu dhabi cars need to pass inspection without breaking the bank. Has anyone here replaced just the cat on an older Nissan and seen immediate improvement in power and gas mileage? Also wondering if I should try one of those cleaner additives first or if that’s just throwing money away.