I believe and to an extend i have experienced small gains, to get a good to great sex life, you need to be physically fit in everyway, all your organs, from the brain, nervous system, testicles prostate, all fuel your sexual system.
Exercise increases blood flood to the penis, good nutrition and the right nutritional supplements and a good diet of protiens, good oils and fats, good carbs etc fuel all organs especially those that drive your sexual appetite.
You can also work out you pc muscles that help control your erection and how tite your anus is.
http://www.betterman.com/penis-enlargement-forum/ this is a list of stretches and squeezes to add length and girth your dick over time, not 2 inches in one month.
kegels to strengthen the pc muscles for stronger erections and titer assholes, because those muscles are connected to the ones in your penis.
Overall improved sexual performances starts with overall fitness and health including direct work to your penis!