100NL 2ndpair 3bpot vs aggro reg

4bet is almost always better, 16% is not a frequency I would slowplay KK against, looks solid. you just give your opponent a chance to crack your kings while his 3betting range is making good money overall vs your btn open

on the turn I think you should fold, seems the type of guy to barrel any Ax here but definitely not QQ JJ Tx with this sizing.

on the river it's very hard for him to be bluffing. if he had 89 now has a str8, you have 2 healthy blockers to KQ KJ and on this board you have Ax AT TT 66 in your range so i guess it's unlikely he just barrel bluffs pure air with these sizings oop and even if he is you still don't have to bluffcatch this hand because you have a lot of other nutted hands that will get here.

because of his timings I think I put him on TT, maybe AK/AQ

I would say 4b > call. 16% isn't anything super wide anyways. I'd definitely get to the river with this hand but given how many Ax hands you have in your range by the river, I don't think you need to call with this combo. Ofc, if you think he's bluffing too much, calling is fine.

You said 4bet is better than call because 16% is not too wide, but did you notice his maniac cbet stats on each street he is bluff heavy?

Seems that he doesnt have leak vs 4bet and with KK with 4bet we have clear value off course, but is it really higher than calling down vs maniac IP.? I would slowplay all premiums.
If you slowplay premiums, you will have high equity vs his range on each street on most boards.
In Matt's book, he explained that flatting AA vs 3bet vs most regs is higher EV than 4betting it, especially IP. So vs postflop maniacs it is even better to flat.

I am wondering how can this guy be winning reg with such a postflop stats. I would exploit him by flatting all premiums and pushing turn with value that needs protection and draws, and would call down with hands that need less protection.

It isn't exactly simple to evaluate the ev of calling a certain hand preflop. According to my previous analysis of slowplaying QQ/KK preflop, it isn't really worth it when ranges are wide. There's so much ev in just coolering small blind preflop.