I have a 1997 80"evo. Just have valves done 6 months ago and bored 10 over 1 and a half ago. Last week I started hearing a whirling noise. Increases and decreases with engine. Stumped!! I'm planning on tearing it down this winter anyway but still wanted to know. Also what type or size cam should I install. Just want a good sound. So many out there. Thanks!