good hedder paint

They wont be hitting the ground.... i'm currently trying to decide wich headers and what tube diameter to go with to put on my 360 magnum that is in my four wheel drive truck. so the flowtechs are 150 bucks and have a 1.625 inch diamiter tube and the hedmans i can get used for 100 bucks and are 1 5/8 tube diamiter. The truck has brand new exhaust pipe on it but it is only 2 inch exhaust pipe and i wish it was 2 1/4 inch exhaust pipe, but i have been told by others that 2 inch exhaust pipe is better on a four wheel drive truck because it will keep the low end torque better then the 2 1/4 inch exhaust pipe and that the 2 inch will have better throttle response vs the 2 1/4, any truth to this? or is the 2 1/4 just the better siz to go with? it will just make me sick if i have to go get brand new 2 1/4 inch exhaust pipe put on this truck because the 2 inch pipe like i said is brand new. brand new dualed out exhaust with 2 inch pipe. i have always ran 2 1/4 so i dont know much about 2 inch exhust pipe i dont know if it helps with torque or hurts it or what?