thats crazy, standard last year was 5-10%. Recently seen alot people put 12% in their cartridges and are satisfied. How are you getting away with 1.5% terps that seems like so little. My carts are 8-10% terpenes and take atleast an hour for the liquid to move when flipped upside down. Its not really a matter of dilution for me, its a matter of having a very tasty cart that still gets you soaring.
The live resin carts you see floating around are testing in at 12%+ terpenes and i dont think those are too high, incredibly good flavor.
I havent noticed any harsher feeling when increasing terpene content, are you using food grade or cannabis derived terpenes? i use cannabis derived terpenes.
The only bad side effects ive noticed with higher terpene concentration is that it makes you sneeze.