Spark Plugs and Wires?

I took my 97 wrangler into the shop a couple days ago to get some work done on the power steering. I also mentioned to the mechanic that i was getting poor mileage ( 2.5 4cyl getting 17mpg ). He told me that it was probably because of my spark plugs and wires, and that most jeeps dont like Bosch plugs or wires (which are in my jeep now). Is this true? If so, why? What would be a good replacement and how much should this improve my mileage?

I have an 89 Wrangler with the 2.5 and runs it GREAT with the Bosch plugs ( 4 electrode platinum ). The problem with smaller motors is they work harder and usually operate at a higher rpm which means you need to change plugs more often. Here's a couple more tips that have helped my 4 cylinder pull 33" tires with no sweat: I use an air intake system made by Air Raid with a K&N filter, colder thermostat ,160 degrees which I think might fool the computer enough to think it needs a richer mixture and full synthetic oil to reduce friction especially in hot weather.