Thanks for the detailed reply. All I know about the motor (bought it with 99,xxx miles and currently at 113,xxx) is I have a loss of compression on cylinder 1 and a hide cylinder error as a result. I first took it to any reputable warranty shop that was available as the shop I bought the Q7 from, meaning I basically picked it up at Manheim and drove it 11 hours home and paid them the fees and got a loan to pay them back for the cost of the car at the auction and who is a good friend of mine, was not in a position to work on it. But I got it at such a deal, I paid $5100 for an extended warranty. I am glad I did. My friend said he will try to squeeze it in so I told the first shop I will go elsewhere and. Currently it’s still sitting. The first shop wrote up 2 invoices, 1) new long block crate motor and swap parts from my motor 2) a yard motor with equivalent mileage. I wanted a newer motor but not brand new as it would eat up too much of my warranty. I found many within a 5hr drive with low miles in the 30k range and that is why my friend said he’d do the warranty work. I just need him to free up some time to get the warranty approved. But still not sure if it’s a stuck valve or a scored cylinder. I told him I’ll stop by this week to see if I can help with anything so he can get the ball rolling but he has a big exotic car show this week so he has no time.
As for the cats, I would rather gut them them take the $700 risk of not liking the sound the downpipes have been known to make that I hear most hate, especially on a luxury normally quite Q7. As far as I know, the 4M through JHM is a 207mm crank pulley, a catless tune if I go that route and a TCU flash as well. No other mods are available through them and they have strong suggestions on not porting the blower. So I will only be able to push that motor so much, but like I said, rare opportunity to tune it so I will deal with 425hp (give or take) on Audis heaviest vehicle they have the 3.0L in