have a stock 1998 502efi with ( az speed and marine ecu repr., adj fuel reg, k+N FILTER " AND MSD IGNIT ADDING AFTER MARKET EXHAUST. was told that by adding 50lb injectors would increase perf ? ALSO WAS THINKING OF ADDING NEW CAM > ANY OPINIONS?

I believe in having someone with a clue designing the specific power I want. That someone would have done it many times before and can tell me the plusses and minuses. My experience has been that just adding a little something here or there usually has little or no effect on overall performance. It can sometimes cause problems. It's the proven combinations of things that start to make power. Have an experienced marine engine builder give you some recommendations for power upgrades. You may be happier with the results.

26 sonic I did the same mods, but I have a question. Did you change your thermostat from 160 to 140 I was told I had to but now my motor seems to load up when I am idleing around. Iput all the mods on during the winter and really don't know the cause of it. bought the re programmed ecu off another oso member tried calling arizona marine to ask about the thermostat change and can't seem to get a straight answer. I'am thinking that the motor is still in cold mode since my temp never rises above145 when idleing around.

Adding more fuel will only cause the engine to run richer, not add power. To add power you must flow more air through the engine. It's this additional air that requires more fuel. Most of the components you've added have costed money, but really havn't added power. If you have stock manifolds, ditch them for some good tuned manifolds or even headers if you have the $$. The exhaust will get you around 30hp. Now you can add a cam.

with just the super tune kit from az speed and marine , i did'nt and was'nt told to change the thermostat . i have my ngk plugs gapped at .40 and have checked them a couple of times and the are burning the right color .

cord , i plan on adding new exhaust next week, would you think by adding the az speed and marine " short runner intake manifolds" that flow more air that this would make a difference ? later i may add a cam.

they are right contact some one on here with hot rod back ground ,let them tell you how to do it step by step !
I've got friends who have had no luck with the AZ kit ,the Cam and heads, and exhaust do better on a 502 you can get 630+ h.p. easy with the right stuff not just throwing money at the thing

If a catalog listed every trick item at a 10-20hp gain and you threw the entire catalog at your engine, how much power would you be making? Proably 10-20hp more. Stick to the big and expensive items. Exhaust, cam, heads, blowers. That's where the power is.

thats right cord ,damn these quick h.p. tricks they just rip off the guy who knows just alittle about boats ,