The pump doesn't doesn't have to be silent but my car is pretty quiet so if the pumps on the louder side will certainly be heard. My car is likely around 675hp so I think the comp 140 should keep up but I'm thinking a return regulator & line is in my future. If I stick with the 140 I won't have to replace my whole fuel system and being that I'm undecided on what to buy I might just send my Mallory away for a rebuild over winter. I might just limp it through a couple more months then I'll be done driving it for the season in anyways.