air injection works direct from air cleaner unit. you can buy a kit from norman hyde or jenks bolts or if you are in usa new bonneville .com. when you remove dont throw parts away. if you have to replace due to emission laws, note when blocking off air cleaner housing use a sealant. as i had problem with mine blowing out. you can also fit a unifilter makes the engine breath better.what size jets are you planning to fit? to small you will get exhaust popping. i have 125 main and 145 pilot and change needle. i have not changed my needle yet. hope this is helpfull pete