I think it was just shy of $200.

The seller I bought them from on eBay no longer has them. Here is an equivalent though. Performance Exhaust Manifold Headers FITS BMW E46 E39 Z3 2.5L 2.8L 3.0L L6 | eBay

Rookie, how are you going to handle cats? Two separate streams like OEM or merge the headers into a single? Or, there are some pricey two-in, two-out cats that have a single body. That could work, but they look big.

Also, I see no reason why you couldn't weld a fueling 02 bung in the OEM position into the middle primary (right off the head) of any set of stainless manifolds.

lo_jack:

I was planning to keep the true dual exhaust intact, having the two header outlets meet two mid-pipes with CATs welded into the front of them (or wherever they fit under the truck best). I want to keep the SuperSprint aft sections as well. Wonder how they will sound with the headers... :dunno:

I did something very similar on my E46 M3 two years ago - headers (Status Gruppe ceramic-coated) dump into reworked mid-pipes, each with a 400-cell aftermarket CATs. We put O2 bungs on the aft part of the CAT's and have had no SES light issues.

E46 M3 aftermarket exhaust parts are easier to find than the E53 X5 3.0i....

Headers are not all created equal. If all you want is the engine to sound better just find someone who has had the least problem getting a particular offering installed. Some may slide right in place, plug and play, others may require removing a bunch of stuff to get clearance to get them in place and run up the cost modifying the exhaust.

Buying headers that improve performance is much more difficult. There's a lot of R&D on a dyno to design a HP/TQ curve best for the engine application. If performance is any concern I suggest purchasing from a supplier that provides before and after dyno runs and also after with a matching tune. If that is not in the budget I suggest just getting a tune for performance and low restriction mufflers for better sound.

Whether purchasing headers for sound or performance equal length is important.

I started on this yesterday. It seems like these have to go on and off nearly entirely from below. Does it help at all to take off the wheel and the fender liner, or does this just have to be a beast?