We recommend professional installation. If you have any questions regarding installation, adjustment, or any other questions please call prior to installing or adjusting. Do not adjust the Boss coilovers spring preload more than 3" of thread showing below the black adjustment ring. If there is more than 3" of threads showing below the black adjustment ring, this will void any and all warranties. Our contact phone line is 303 518-2114. Please call if you need any info on our Boss Coilovers or other products.