The ones that are sent from a tuner over the internet. A dyno tune is a good bit better than just telling someone what mods you have and making a tune for you hundreds/thousands of miles away.

 

damn that sux for me i bought a BAMA tunner and every time i needed a tune for the few mods i have they have sent me one but i can see where getting it dyno tune would be better the the bama tune

 

and could you explain to me whats the IMIRC stands for and whats the diffrence between b and c heads and which is better

 

IMRC = Intake Manifold Runner Controllers
there is a plate inbetween your intake and heads that has round and squarish ports the round ports have butterfly valves that open up at 3250rpm's. These stay closed on the lower rpm's to help with low end torque.
I'm not going to get into the B vs C head and which is better. If you google it you will find 10 million reason why each is better. MY opinion you have the B heads and your going Turbo I would just stick with them

 

awesome ook thank you for the info ..

 

also i have read about people deleting them or replacing them for aftermarket one what diffrence does it make ?