With the wealth of information to look through on the WWW, one can find all the information they want. But I'd really like to ask some of your guy's personal opinions.

only important part to read:
I'm looking for the fastest spooling turbo that can handle about 225wtq at 8,000 RPM.
A to create a flat torque curve via a boost control solenoid from the boost threshold all the way to redline.

​​the remaining is caffeine rambling:
I'm also not familiar with some of the newer gen Garrett stuff. All i know a little about about are efr line up and gt25's. The car currently has a GT2554R which i love it's a phenomenal turbo for autocross & street. I am somehow able to get it to make 285whp on e85 (dynojet #'s). I haven't tried to go beyond 7k rpm yet. 11.5-12.5psi at 0-4k rpm tapered from 12.5psi @ 5.5k rpm to 15.5psi at redline is what yields the 218-225wtq across the whole rev range. I can't say enough how much i love it but i plan to increase the rpm to 8k as well as mostly only run it on 93 gasoline. So pretty sure I'll be selling a 2554R. What should replace it?

 

What manifold do you have?

The 2860 or 287x won't give you the spool you want I don't think.

 

It's just the ebay cast iron log manifold currently paired to the gt2554r. Would not mind re using it because it's so reliable or I might change to what's needed to run a different turbo. So that's a variable

 

It looks to me so far from the few bits I've seen that initially the GT2860r starts to build power 500rpm later than the GT2554r.
The 2554r definitely builds boost from threshold to target in a rapid short window tho and really shows how long the 2860 takes to ramp up in comparison.

Idk if the efr6258 is just ever so slightly too large or would be better

 

I have run a 2554 on a begi setup, and a 2871 on my absurdflow ramhorn. The 2554 still spooled much better on the low end. I really loved my 2554 when driving around in DC traffic.

Going to an EFR will require a new manifold. It does not provide room behind the EFR for the down pipe.

 

oh yes the efr also requires a new down pipe. I would prefer to keep using the flyin miata cast downpipe elbow if possible. Idk how much more reliable vband downpipes made of stainless are yet. It is a compromise between roadtrip car and for autocross or rare track

Sorry about all the half written and re edited posts. It sucks being on my phone.

for a purchase of $2k+ I'd rather prioritise getting xidas before a EFR. But i would not mind learning more about how the spool up of the efr compares to the gt28's. I'm about to look that up. So far i imagine it likely builds boost more like a 2554r but might have quite the higher threshold to start. Good transient response

As for reliability in the long term aren't EFR's ever so slightly more prone to mishaps being slightly more fragile than Garrett ball bearing turbos?
You can find pictures of turbine wheel blade explosions on EFR's online not long after the line was introduced. But idk

 

The Garrett GTX2860R Turbo looks actually very good and the price is better than EFR as well. And matches my pre exising hotside so the price would far exceed the efr for me. So i wish they made a gen 2 version of the 2554r or 60r omg that would be flawless for my goals. The gen2 2560r would be flawless victory lol ✌