How many horsepower one needs to gain in order to see some actual changes in acceleration times? Does installing a cold air intake and an exhaust really translates into any noticeable acceleration improvement?
Thank You

 

depends what you are looking for and what you are adding on. I just threw on a RRM CAI yesterday. I hanv't dropped 2 seconds off my 1/4 or anything, but I can notice that it pulls alot harder between 2500 and 5000 RPMs. At most, its a 5% HP gain in my case. As you asked, I do notice the difference. But, I also notice a much stronger sound. No one ever noticed me on he road before, but it seemed someone at almost every stoplight wanted to race me as soon as I put it on.

If you are really only interested in accel, read the thread about a NA RA shooting for a 13sec 1/4. Or just get in line like the rest of us and wait for the turbo