hi all sifus, may i know will the drop-in filter increase the low end power significantly or just cant feel it at all? and is there any recommended shop to do the modification? i am driving viva 660 btw, the accelerate power is very bad(somewhere 1-3k rpm, after 3k rpm then i only feel the power come), wish to get some mod to increase it, at least i can feel the different. Thank you all.