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Checking cats

916 Views 3 Replies 3 Participants Last post by  chevyman992002
I recall reading somewhere that you can check your cat(s) with a temp gun. But I can't remember what the allowable temp change from front to back is. Does anyone know what the limits are? 10% comes to mind but I'm just not sure.
I have 1 thats 315 front and 325 rear. The other is 311 front and 385 rear.
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