08 Jetta Sputtering at 60mph not before

also, the sputtering is right below the driver's side, literally under my seat. not coming from the engine or rear.

I equate sputtering with an engine misfire. It sounds like you are describing a 60 mph vibration in the left front wheel. Try swapping tires around to see if it the tire or the rotating mechanisms in that corner. It could be a bent rim or sometimes the tread inside the tire break if your girlfriend smacked a pothole or curb.

i have no idea, so could be. but it sounds as if the muffler although i'm aware it's not the muffler is backfiring, that's the type of sound it's making.

If it was a leak in the exhaust, it would do it all the time. It's hard to diagnose a sound without hearing it. You could take it to a shop or have someone you work with hear it. They might be able to tell just from the sound.

i understand, i took it to my regular shop, they rode with me and heard the sound hit at 60mph exactly as we drove down the highway.....said he wasn't sure and it was weird, have appointment in a few days, just seeing if i could find info beforehand. it goes away as soon as i drop under 60mph and only hits when i hit 60mph. drove it around town for about 2 hours after this today, no problems at all, no noise, no rough ideal, nothing. drove and sounded perfect.

carbon buildup maybe the harder run blue it out some, cancel that trip and run some seafoam true the intake. yes check oil for no overfill, I know what's out there

turned out to be the splash guard not put back into place by the oil change