Arttu

I would simply forget about that 9000 rpm spec for the rods. They seem to have that for pretty much all their rods, including GSX-R1000 ones which are routinely revved up to 12000+ without issues...

In theory, yes. But they also have their own problems why they aren't the best solution for modified engines. Usually combining TPS and MAP in some way is a good solution for bike engines.

Smoothness of the MAP signal isn't the problem. As you say it can be sorted out relatively easily. The main problem is that usually with individual throttles the measured pressure doesn't correlate very well with load / air flow. When you gradually open the throttle the pressure increases but reaches the ambient pressure (or boost) pretty quickly. Beyond that point there is no change in the pressure but actual air flow still keeps increasing while the throttle gets more open. Systems with single throttle and common plenum (=typical car engine) don't have this problem. Engine phase detection with MAP is somewhat different problem. There you want a clear jump in the MAP reading during the intake stroke but accuracy of measured pressure isn't important.

No, it's not. At least as long as we speak about individual throttles per cylinder.

Advice: https://www.proboost.fi/motorcycle-turbo-kits

It depends heavily on injector size. With relatively small injectors, like up to around 500cc/min, you can use even a dead head rail without any major issues. Like most of the stock EFI bikes do. But with bigger injectors the fuel pressure pulsing gets stronger and may start causing all kind weird tuning issues. Flow through fuel rail is the first and most important improvement. When fuel is flowing through the rail back to the regulator the flow in the rail doesn't need to stop and start moving again when the injector pulse. This reduces pulsing a lot and usually it's good enough even for pretty extreme injectors if the rail ID is big enough. Pressure compensators / accumulators can improve situation even further but like said usually they aren't necessary. Only cases where I really had needed them are nitro engines with 7000+cc/min injectors...

Yeah, ideally you want to point the injectors towards the valves but in reality it isn't that critical. However, further down to the port you can get the spray before hitting the walls the better. All this matter quite little at full throttle and high rpm when the air flow is strong enough to keep the fuel moving. But at lower rpms it may have noticeable effect. Especially during throttle transitions. More "wet" intake wall surface you have more you need acceleration enrichment. And excessive acceleration enrichment will cause all kind side effects that can be difficult to compensate. But as said above, don't worry too much about this. Do what you can to get them at good angle but compromises are fine.

No. It needs just reliable boost pressure sensing and then fuel delivery can be programmed to whatever is needed. Generally speaking.

Here are few pics. Hopefully they give some idea. Basically you swap around the bodies so that you get the cable mechanism in the middle. Then you take now unused linkage bracket and bolt it on top of the cable mechanism. If I recall correctly I had to bend it slightly to make contact to the tab of the next throttle. But no any welding was needed.

Well, in my case it definitely has hold up better than an average spraycan stuff...

I have had mine coated a couple times, with Techline and Cerakote coatings. As conclusion I would say they tolerate high temperatures very well but water and dirt cause problems. So the coating stays pretty well on the spots which stay clean but the parts that get dirt blasting from the front wheel start rusting pretty quickly. I think Techline was holding better than Cerakote but can't say for sure...

For reference, an AEM 400lph pump started to run out of the flow around 750hp, on E85 fuel. That was at 4.8 bar / 70 psi total pressure, 3 bar base + boost.

Megasquirt 2 and 3 based ECUs are good choices, at least regarding the software options. Unfortunately bike oriented hardware variants (small and sealed) are a bit limited. But for example the Microsquirt is a good and proven choice. Some unofficial clones could be worth of checking as well. Other budget oriented options which should be ok are Speeduino and RusEFI but I don't have any personal experience about them so can't say anything about their pros and cons. Or if you want to invest a bit more the MaxxECU Mini is one good option too. Limited IOs but software is really flexible.

For sure you will learn a thing or two while trying. But trust me, there is enough to learn for a while even if you start with a ready-made ECU. Or at least for most of the people. I have seen quite many more or less successful EFI conversions over the years. Usually ones that start with ambitious plans and aim to re-invent the wheel are ones which never get running...

Never heard anyone doing that and I'm not familiar enough with today's PLCs to say if it's doable or not. But I'm pretty confident that there is virtually no any sensible reason to even attempt that, compared to using any proper ECU. Except if you want to take it as a "can I do it?" challenge...