vortec

I've got a 2000 jimmy sle. 4.3l v6 vortec 4x4 drive. I'm looking to put flow master super 44's on there, but whenever i input my vehicle, it says the exhaust is not compatible with the vehicle. thing is, i used to have a 98 chevy s10, and when i plug that in, it says the exhaust is compatible...

I have a 2000 GMC Sierra SLE Z71, 217,000 Miles. The truck sat for about 8 months and yesterday I renewed the tags and changed the oil. The truck had normally ran between 40-45 on the OP Gauge, now it's idling on 45-50 and now at 40mph it's about 60. I don't remember it being this high...

Dealer says use oil life, so i've been going by oil life. Truck has 83,000 km. At 30% oil life and 9500 km since last oil change, oil level was down (caught me by surprise being a newer vehicle, I don't check oil as often as I should and now I will) at tip of dipstick. Added a litre and still...