Yes because it is designed for the Grand Prix system which is different from the Bonnevilles.

Thats what I am in the process of doing on my STE (I have only the right side put on, I haven't had time to do the left side), but they are awesome. They are straight through mufflers, like a resonator, so they flow very well, but they still quiet the car down. Thats definately what I would do if I were you. I don't even have both of them on my car yet, and I am impressed.

Shawn

I couldnt have said it better myself

Update - FLASH ALERT.

I pulled out trani dipstick tube to loosen off the last of the rear manifold bolts.
You can get at all the bolts from the top side. From underneath it'* difficult to get enough force on the rachet.
Anyways....I compared the original dipstick tube and dipstick to the new offset dipstick & tube from the earlier model GTP as recommended by the group....and there are major differences that are very worthy of note
The tube itself being offset turns out to be 1/2" longer than the original and the dipstick is longer to make up for it, as you might expect. The original dipstick protrudes about 5/32" more out of the original tube so you wouldn't think that this will make much difference.
WELL, the scales of both sticks are off by about 5/8". That means that if you go by the new scale, you would be adding about one liter or 2 pints more fluid than you should and that could spell disaster
If you try to put the original stick in the new tube, it'* too short by 11/16".
The scale of the new stick is twice that of the old one so 1 pint on the new stick is actually 2 pints.
So I,m going to scribe a new scale to match my old one.
Let me know if you find the same opportunity.

You commented on the headers only being 20 HP. But with rockers, they'll pair up nicely, and collectively have more then they would seperately.

Update - the rear manifold has now been removed.
It was easy although time consuming because I didn't use my air ratchet. :?
It pulled out the bottom even though it was a little tight since I haven't removed the CAT and rest of the exhaust system. I think before I install the new header that I will cut off the CAT to make more room.

One strange detail I thought you might be interested in. While cleaning up the original header bolts with my tap and die set, I noticed that the special stud bolt is metric on one end and imperial on the end that screws into the heads. Dumb mix of standards. :?

On closer examination of the rear manifold I can see how inefficient it really is. The tubes that enter the main body of it protrude inside and must create restriction and turbulence at higher flows. It'* basically a cheap piece and poorly welded.
Kudos for ZZP for offering an option of modified OEM headers as a less costly option

Man...I wish someone would make headers for a series I....patiently waiting [sic]

Note the tube protrusion I was referring to.

Ugly old manifolds. I'm having fun after just being taught by another member finally how to do it.

Here is the comparison between the new (top) and the original trani dipstick tube.
I managed to straighten out the new dipstick * bends in order to lengthen it enough that the add marks are the same as the original one but the full mark is almost twice as high as the original one.