Going from stock turbo to FP Red or BBK-B on 91 is very frustrating experience.
Unless you are into Drag-Racing.
The lag is hard-felt, and here in the Bay Area the traffic is heavy - so if your car is DD stay - don't go there.
The large turbo's don't come into their own until high boost at high rpm.

You should consult professionals, at FFTec in Hayward.
Its a beyond reputable local shop, that has "seen it all, down it all" and supports local racers and daily drivers who use various turbo's.

I can clue you in, what their own personal has chosen: HKS 7460.
Its the most responsive turbo made that is arguably as responsive as stock 10.5, but some argue even more responsive.

On 91 you can make (with cams) about 350whp on Mustang dyno. Compare to stock Evo IX making 225whp on FFTec dyno, to understand what that means.
FP Green may be able to make +5whp or so, but its response and spool are not in the same league.

I took their advice, and both my Evo's are on HKS.
I am beyond pleased, both on 91 and E85.

My advice is to talk to FFTec, and if on budget, shop for a used turbo. I've seen HKS turbos used for as little as $1200-$1300. That is very cheap for the product that is so well engineered and should last for the life-time of the car. FFTec had zero issues with the hKS on their installs, including Evo IX stock block making 435whp on their. That is the flow-limit of HKS (Its approx 490whp DJ, on E85).

 

much revive, such new comments, wow.. sadly I'm still in the process of getting the turbo lol.. to the guy above me, yeah I was tuned by fftec 3 years ago so i know how reputable they are, and I have decided to not get the red and stick with the green for exactly what you mentioned-keeping the car fun in the lower rpms since it's my dd. I will check out the HKS again since you brought it up. I believe there wasn't many reviews (maybe one) of that turbo when I made this thread.

thanks