YZF-Randy6

I have this weird clunking sound that i hear. It only happens when i initially rev the car. Happens before 1k rpms and only happens for like a second. It almost sounds like its coming from the exhaust. Cant really pin point the issue. No noticeable loss in performance, and no burning oil. The sound is hard to capture on video and a bit hard to describe. Best way to describe it would be a metal clank. Car is 2008 EVO X GSR 66K. Since i owned the car have never done any launches or bounced off the rev limiter, just mainly some spirit driving here and there. Cant say about the person who owned it previously since i do not know them. Any advice or similar experience information would be greatly appreciated. I dont believe it's rod knock. Mainly cause no loss in performance its been doing it for about a month now, and never had a CEL flash or come on. Also it is only for a split second and does not rise or fall with the rpms. Its also a one time clank. Not multiple clanks each time it makes the noise. Sorry if my descriptions are inadequate. Describing engine sounds can be quite a task. Thanks in advance for any help or advice.