i would vote piston,never pulled them apart,it was easy to just swap them out.
but after the failure it was way easy to cock....so my money is on the pistin failing.
the first batch of titans made had piston failures,my local walmart had over 12 brought back in 1 mth.
so i opted for a remanufactured one for $99.....worth 3 times that in my opinion.
a .22 reman that can drop doves from long distances.....i was offered $200 for my titan with scope....i turned it down.the guy knew it was a $99 reman too.its hard to get a good titan.
point is not every piston is created equally,you read stories of thousands of shots fired,then stories of less than 200 rounds fired......its a trial and error kinda thing.when you get a good one youll know!
my trail xl hits 940 with cphp's stock......ill never part with that one.
everywhere i read states in the 850 range