The TeraFlex 2012-2018 JK: Exhaust Spacer Kit is required for all 2012-2018 JK Wrangler models with 2.5" or more lift to prevent contact between the front driveshaft and the exhaust crossover pipe during suspension down travel. Exhaust Spacers install between the exhaust header flanges and the crossover pipe flanges to move the crossover pipe rearward for proper driveshaft clearance.