Thanks for your answers~!
I didnt know that thing must removed for install the exhaust.. but the thing is.. that mechanic who installed exhaust on my Z didnt coverd the hoses with heat wrap.. can I just buy some heat wrap and cover the hoses? I'm think to lift the right rear side with using lifter when I use when I got a flat tire.. can I just lift the rear side and wrap those hoses by my self? even though I already installed HKS exhaust? and where can I buy those heat wraps?...