the diffrence in pistons is called pdd which stands for piston dome displcement. the higher the number the more compression. i just kinda wanted to share some info for the person who started this thread. anyway a stock b16 piston has around a 6. something and the b16b has an 8. something and an itr piston has a 4. something this is why it is stupid that some people pull their b16 pistons and put itr pistons they just lowerd their number