I've already done lots of searching in the last month or so on this very question and have definitely found some valuable input obviously, but none for my specific slew of modifications. I even talked to Keith at Flyin Miata (as I'll be buying the remainder of my parts from them). I trust him and Flyin Miata plenty but am just looking for other view points.
He suggested I go with the GT2560R as i'm not giving up much in way of spool (<500rpms worth), and it'd also be more efficient.
My counter to this however, is that this is primarily a street car that's driven every day to work. It DOES see track time however. I really love the idea of instantaneous spool, but am afraid the trade off in power potential is too great.
As far as power levels, I'm honestly not sure where I want to be, but I know my starting goal is ~210whp. Not sure yet if I'd want more than that.
What and how much (if anything) am I giving up or gaining with either of these turbos, given the below set up? Will my below set up allow the 2560 to spool well enough for me not to notice? Subtle or not.
I'm running a healthy Long nose 1.6 (~125k miles, good compression) with stock internals, and am "planning" to keep it that way. This is my only car so a 1.8 swap and being without the car for a little while is a bit of a challenge. I won't delve further into more reasons though since it's talked about a million times already.
I've already had Abe @ Artech make me a Manifold and 3.0" divorced downpipe. (super beautiful, and Abe was amazing to work with btw) He also provided a stainless water and oil line kit. This manifold will work with either of the above turbo units.
Motor: Stock longnose 1.6
ECU: Megasquirt PNP2 with Innovate MTX-L Wideband
Fuel: 610cc Flow Force injectors (from Trackspeed)
Exhaust: Artech Manifold > Artech 3" Downpipe > Enthuza 3" Cat/Exhaust
Clutch: FM Happy Meal (Stage 1)
Driveline/Diff: 3.9 Torsen / all associated components
Turbo: Gt2554R vs Gt2560R (Provided by Flyin' Miata)
Everything else: the rest of the kit (intercooler piping, intake, odds and ends, turbo itself) will be Flyin' Miata FMII kit.
Not sure if I should list anything else.
Apologies if this seems like a wasteful question. I'm aware the two turbos are very similar, but they are described different enough to warrant a thread I think.
Thanks much for any input.