I mountd mine in one of the dual pipes after the header before they merge (I have a single exhaust). Make sure you use a wideband sensor - the narrow band units are useless for tuning carbs. I have a kit from AEM which I was able to get on ebay for only 225, new, in box. It works extremely well and has been fundamental to getting my car to run right. It also revealed a very dangerous lean condition at full throttle at hi revs that I thought was just something loose rattling under the hood, but was actually my engine thinking about exploding. It paid for itself right there.