Ok second question on my new to me truck. 02 silverado Z71 5.3L 4x4. This truck seems to have good power but I have never driven any other silverado to really compare her to. As I can tell there are no power upgrades under the hood. There is a cat back exhaust that exits just befor the rear wheel duall pipes. I have not looked but I am guessing it is a gibson or something very similar. sounds like a single chamber, very load and raspy on WOT. I gave this info so you have an understanding of the trans concearn I am having. The 1st to second shift point is fixed at 17 mph in D and 3 on the PRNDL. she will not shift into second at all before this unless I shift to 2 manually. It is very firm and snappy. I have gotten used to driving it this way and can ease the firmness by letting off slightly while accelling. The other shift concearn is the 2-3. While entering the highway at light throttle EI not speeding to merge just sunday driving the 1-2 feels good but the 2-3 feels slightly slow and if I hold the throttle at the same point as I am accelling i can hear the engine rev slightly through the shift point. No check engine light, fluid is full hot and on a level surface engine running. from everyting I can tell the previous owner did take care of the truck. Due to the exhaust and the rest of the accessories on the truck I am questioning if he may have put in a computer mod to change the shift points and firmness. I feel the need to put in a higher level octain to prevent some slight knock concearns I had and this did fix the problem. What do you think? should I be concearned about the 2-3 slip or is this normal for the silverado. Any thoughts would be entertained thank you for reading I appologize for the long post but I get annoyed when people ask for help but give no info to work with lol

 

the 5.3 and 4l60e have been great but some people have had problems with the tranny. my dad has a 97 van with the 4l80e and had a shift problem with it slipping out of 4th gear. it ended up being his shift solenoids in the tranny. parts werent the most expensive and easy to change. >100$ <150$