i have a 2004 lq4 wanting to know a cam or should i leave stock for towing and pulling? also heard the later lq4 like 2004 already had the same cam as the lq9 ? is it true? going to install in my 2000 z71 ext cab. what about a set of good pistons?also running a powerdyne 9 psi charger. any suggestion would be grealy appreciated. thanks