So even though I was very skeptic about aftermarket MAFs I kept hearing a lot of good things about HP and MPG increases when using them. I bought a used Granatelli online but before I even got it I started hearing better things about the JET so I bought one of those online also. I got it from a guy on ebay who said his broke and he got a replacement one but changed his setup and couldn't use it anymore so it was never even used. I bought my truck just about a month ago and the only thing I had done to it was put a Hypertech programmer on it. I monitored the long term fuel trims and found that my truck was running a little lean but not too bad, an average fuel trim of about +9%. I put the Jet Maf on and could definately tell that there was a power increase with it but after a few days I noticed the check engine light had come on. It turned out that it had come on because of a lean condition, so I monitored the fuel trims and they were about +20-25% with the MAF. Today I got some MAF cleaner and cleaned the MAF as well as installed a Volant CAI with the ram air scoop and uninstalled my Hypertech so that I wouldn't have increased timing while running lean. On my way to work today the fuel trims are a little better, around +15-20% but still a lot higher than I would like. Is this a common problem with the aftermarket MAFs? I got the Granatelli in the mail which I have up for sale on ebay and boy oh boy did it look cheap. The Jet one looks alot better, it appears Jet removes the honeycomb and cuts some holes in the bar going across the middle for a smooth professional look. The Granatelli does not look like something I want to put in my truck, the honeycomb and the bar going across the middle are removed and the black plastic bar going across is cut down as far as possible, making the sensor wires supported by a lot less. Anyways, I think both of them are going on ebay, but has anybody else had problems like this? I'm sure a lot of people think they add HP and MPG which they do because your truck is running so lean but it is not the way I want my truck to run and how can they sell a product that makes your check engine light come on?