Ok,looking for no cost or low cost tips. Here's mine from old drag racing days. When changing plugs select plugs that position themselves with the grounding electrodes toward the bottom, this will open the spark to the combustion chamber resulting in ?%hp. Always makes me feel better.
Who has other tips?

Degreeing plugs is an old trick but nearly useless......Try and degree some of the multi-tips out there now.....

On the big block engines--valve notch the cylinders. angle grind the cylinder out to about 1/16 inch from the head gasket at the valve pockets and down to about 1/16 above the top ring mark on the cylinder. This can add 25 to 30 HP.
VALVE NOTCH

[ 02-10-2002: Message edited by: Tinkerboater ]

Indexing the spark plugs is needed for high dome pistons. It is said there is a very slight increase in power if the spark is directed towards the intake valve. It is so minor I doubt it is worth the time involved.

Notching the block is a very good idea for unshrouding the intake valve. If building a new motor you might want to use offset dowels in the block as well. This will shift the intake valve a few more thousandths further away from the block unshrouding the intake valve even further. Offset dowels cost a couple of bucks at most speed shops.

Cheap tip: marry a mechanic