I definitely remember your engine thread about your tentioner failing.
how did all the warranty claims go? it sounded like a tough time.
if you have forged pistons this sound is completely normal especially with a NA 2.5.
its just a little slap.
and its gonna sound rough until you get it hot (just hotter than it should) that is a performance modification, pull a couple miles up a long hill and it will sound perfect, just like normal.
this sounds out of the ordinary, but the harder you push that motor the more normal it sounds. do a nice hard run in 4th (bout 65/70 is 4000rpms) up a large hill about a mile or two and then just pull over and listen sounds great.
forged piston expand more than cast pistons(stock), so engine builders leave more piston to wall clearance. this allows more wobble from the wrist pin allowing the piston skirt to "slap" around more than a cast piston and just causes more noise until it gets hot and expands far enough to limit the play and reduce slap.
glad to see your up past 10k on this build. you can always send your oil to blackstone labs. its like 23 bucks to get a definitive result if you have rod knock since they search for contaminates in your oil.. such as metal shavings from rod knock.