I have trick flow rods and LS6 springs I dont really notice it anymore than when it was stock. Heres an easy solution: PULL UR MUFFLER OFF! haha

 

My set up sounds very quite. When doing my valvetrain set up I use checker springs and bleed my lifters down a least a couple of times. I like to reach 22 ft lbs within 1/2 to 3/4 of a turn. If my pushrod is too long it will take more turns to get to 22 ft lbs, because the valve will start too open. Just the opposite of what I use to think? I have had valves hit the pistons due to, pushrods to long. I have stock L92 heads not milled and the camshaft in my sig and using 7.325" length pushrods. When my pushrods were to long, my valvetrain was very noisey, real bad at 1800 to 2100 rpms. And the engine seemed like it would not rev easy. Bad valve train bounce on the 2-3 shift at the track, felt as though the transmission did not want to shift. While this was happening my valves were barely hitting the pistons.

This weekend in at the race track I was able to turn my motor to 7200 rpms with my setup.

 

if you want to get rid of the sewing machine noise get a set of stud mounted full roller rockers and follow the instructions to lash them then you dont need to worry about the push rod length. it will set you back about 5 bills though for a good set of rockers