Yep, cams are different so is compression. But 31's are larger than stock. Measure in on a mile or compare GPS to speedo. See how much of a difference.
http://www.4x4wire.com/toyota/faq/parts/
http://www.off-road.com/trucks-4x4/toyota-4-cyl-engine-information-18589.html
Hope this helps
http://www.4x4wire.com/toyota/faq/parts/
http://www.off-road.com/trucks-4x4/toyota-4-cyl-engine-information-18589.html
Hope this helps