I've had new 496 CMI headers tacked onto the stock motor this winter. She's a 2004 27 fever with a Bravo 1. Any recommendations on the new prop?

I'm turning a 23P labbed Hydro 4 blade with a similar set up. Check with Brett at BBlades, he can dial you in with exactly what you need. He'll probalbly set you up with a 24 Bravo One.

My setup is exactly the same: 496HO and CMI sport tubes.
The only slight difference is that I have Bravo XR (19" X dimension), which possibly absorbs a bit more than standard Bravo.
Anyway, I'm hitting a straight 70 with a 4 blades 26" L/H Bravo prop, at 5100 RPM.
I did talk to Brett, he confirmed that's just about all I can expect in top speed with this setup.
He suggested that a 5 blades Maximus should improve acceleration without hurting too much on top speed, but I didn't give that a try (yet).

Had a 1998 with 502 mpi, 415 HP I used a 24 Hydro I think 5100rpms and hit 71 was the best I could get.

26" Bravo 1 should be your prop.

I think you might have a 1.65 drive ratio ? If so a labbed 30 bravo would be about right . I have the same set up minus the headers and am running 69.5 gps stock 28 b1 lefty .. I bought a 30 lab but it is a little slow out of the hole .. I am happy with the 28 .. been thinking about a maximus or 5 blade hydro p5x ..

28p LH, depending on the water... I get 67-70 but some crazy list to the left when getting on plane...But I dont have CMI's so you might see better?

With a LH prop? Now that's weird!

Some 27's came with RH set up, I also had a 2001 27 Fever w/500efi 5400rpms came with a 25 Hydro RH gps 74-76 all day, speedo would hit 78-80. AND IT LISTED TO THE LEFT LIKE A BI%^*

I understand that, with a RH prop.
But 10K4U says he's spinning a LH prop. With it, if any kind of listing should be expected, that's to stbd!