First of all what's the difference between a cold air intake and a short ram intake? Is getting an intake a good investment? What's a good brand? How much more HP does it add? and is it possible to make your own intake?

 

short ram suck warm air due to the fact that it is short simple
the full intake reaches underneath the car where the cold is
giving a slight diffrence, the noise is also diffrent
longer you get a slight sniffing sound, shorter you hear a more throatier sound(louder at full throttle), everyone goes for the long air pipe
short ram is for the ones who drive alot in the rain,
the gains are expected to be around 5-7 hp on the short ram
and bout 10 hp on the long air, this is all estimate
it is possible to make a custom intake, but probaly not worth it
the intake companies research to make all this possible,
you slap on a sink tube or something of that sort you get gains around a short ram, problems should arise. probaly not worth it
its all up to you and good luck