[HIPPO]

Depending on what pipe you intend to use and on the particular bike, it might work fine with just the pipes.

If it doesn't you need the reflash, and since the reflash is calibrated for the air intake kit you should use it also.

These bikes do not like very low backpressure pipes.

 

[HIPPO]

Still depends on the individual bike, but with that type of pipe it might fly. One way to find out.

On the other hand doing the pipes and the intake and reflash is the way to go as you gain some performance for your money. With the pipes alone, even if it works, all you get is noise. You'll never feel the couple of horses the pipes alone may make.