I have a 2006 Ford Mustang V6 4.0L 210 hp convertible. I recently replaced the exhaust system with 2 flow masters. It's much louder and sounds a bit more impressive. I was also told it increased my horsepower. the installer said it added 25 more horsepower. so now I have a total of 235 hp (i think). What are some other inexpensive ways to increase power and acceleration? I was told K&N air intake systems. they give you a added 7.49 hp but that doesn't seem like much for $300. i'm not a car person so please explain and maybe give links to websites. thank you!