I installed a volo vp12 in my 98sc400. I get about 3 mpg better then before and notice a lil more power. Not much but if u know your car ull b able to tell. I also installed a jdm prom and ya it's not a gimmick. At least not for my car. I lost about 1 mpg hooking up jdm but increase in horse power is great

 

I installed a volo vp12 in my 98sc400. I get about 3 mpg better then before and notice a lil more power. Not much but if u know your car ull b able to tell. I also installed a jdm prom and ya it's not a gimmick. At least not for my car. I lost about 1 mpg hooking up jdm but increase in horse power is great

 

What's a jdm prom? I need to see dyno sheets before I'll consider any performance chip not a gimmick