I have a 2006 velocity with staggered 525's. is there a recommended spark plug other than ac delco? Do I stay with the same heat range or is there a better plug from ac delco that is different than what is currently in the motor?

?????? I just replaced mine today, 2005 525's, the owner manual lists the plugs to be NGK BPR6ES. I wouldn't use anything but NGK

i 100 % agree ngk plugs.

The link below offers some sound advice to consider from a highly respected marine professional, plus i have have seen the same results myself a few times with these engines vs spark plug brands.

http://www.riverdavesplace.com/forum...=1#post1311086

Something to think about is all, Good luck.