yeah probably plugs. check em, since i notice the majority of stock sr swaps seem to run on the rich side, they're probably due. when u pull the old ones, check what gap theyre at. you should be good with .030" gap with a relatively stock sr and your power output, even try .032" since the more gap you can get w/o misfiring, the better.

i suggest ngk bkr7e or 6e whatever teh SR uses stock. theyre like $6 for all four and you can run them anywhere between 3000-10000 miles at a time.