Harry there is no hard feelings from me mate!
The only thing I find to be offensive is if someone tells me I am wrong and their way is better! especially if they have never experienced their way or even mine!
( None of which you have done or meant!)
But others yes!
I respect people doing different things as then they have stuff to share to make others understand of different possibilities!

There is no problem which can't be over come with any setup! It just takes knowledge, Thinking and finally money!

As for the draw through disadvantage you mentioned ( Re backfire!)
All you need to do is look at the big supercharged engines and copy their burst plate design into your manifold!
I know of an A14 inlet manifold setup like this! ( This one has the plate underneath the manifold ( don't know what this was originally for?) Spring loaded so in the event of a backfire it will blow open! ( Springs are rated to compress around 20 psi of pressure)

As for EFI this is what I am fiddleing with now on my Turbo A15 1000!

Cheers Steve!

Summary of technical points. One thing to remember is that a method that works well isn't the only good way. Let's see if I understand this (I'm sure you'll correct me if I misunderstood something)

Intercooler
- Not needed. The first three years of the Porsche 911 Turbo didn't have one (75-77), yet this 3.0 liter turbo outperformed 7.5 liter NA cars.
- Intercooler is worth it as it significantly reduces the temperature of the compressed air, which increases the boost possible with a given octane fuel
- Using an aluminum radiator should be better than nothing. Unless someone actually tested this, we are all just guessing. Radiators can flow a lot of water, and air is easier to pump ... so air should flow through w/o significant restriction. Putting this in front of the car should allow some cooling effect, although obviously not as a much as a purpose-designed cooler.
- An alternative is to use water or alcohol injection. Some OEM applications used water injection (ex. 1962 Oldsmobile Jetfire)

Wastegate
- Used for adjustable control over boost pressure. When the set pressure is exceeded, exhaust is routed around the turbine to go out the tailpipe
- Not needed if you carefully size the turbo to the application (ensuring that at maximum rpm, design boost is not exceeded). Older OEM applications used this method.

Blow-off valve (or recirculation valve)
- preventing the turbo from surging, for example during gear shift or whenever throttle is closed
- Porsche uses these, so obviously they work
a Blow-off intake boost to atmosphere. Boost is lost. Simple, inexpensive
b.Blow-off to compressor inlet (recirculate back through turbo inlet). Used to enhance throttle response: Boost is kept in circuit for immediate availability when throttle is opened again

Carb setup
- Injection is better, allowing better control of mixture
- Draw through was used by many OEM setups. It is reliable, and the simplest otpion. The downside is you can't use an intercooler, as the fuel will condense in the cooler.
- Blow through works well. The main reason to use this over a draw-through is so an intercooler can be used.
a Boxing carb. This allows a more or less stock carb to be used, the outsided pressure balancing the inside pressure
b Unboxed carb. This was a popular OEM method. phunkdotaspok says this can handle 10 psi with a good top-gasket seal. In an NA application, a warped top is not a problem, as there is no pressure in the float chamber. This only becomes important in boosted application.
- Need richer jets to keep air charge cool and prevent detonation

Fuel pump
- Stock fuel pump is good for draw-through setup. It's not enough for a blow-through setup, as 2.5 boost would overpower the fuel pressure
- Using a low-pressure (15 psi) electric pump oughta be good for a 10-12.5 psi boost.
- Needle and seat has trouble holding more than 10 psi fuel pressure. Better to use a secondary 15-psi pump to cut in only when needed.
- Best setup is to use a rising-rate regulator with a high-psi pump. Excess fuel is returned to the tank.

Turbos
- T3 is pretty big for an A12. Needs high rpm, head work, etc
- Mid-80s Nissan Pulsar turbo (E15 engine) has integral wastegate
- go_the_datto actually tried Daihatsu diesel 1.0 turbo on A12. Good response in lower rpm ranges. Two make better twin-turbo application for A12

Boost pressure
- 6-7 psi is what a lot of OEM applications use.
- 10 psi should be possible with a stock A12/A14
- 14.7 lbs gives theoretically double the airflow so max. power would be about 2x stock, but this isn't actually the result. The reason is that the stock induction and exhaust system won't flow this much air under pressure. However, the low rpm torque could approach 2x (at about 2250 rpm) if a small turbo is used. So a 130hp turbo engine will have much more performance than a 130hp NA engine
- 1986 Honda 1.5 liter ran boost of 4.0 bar - that's 300 bhp ... per cylinder with special fuel

Toyota 4A 1600cc engines
- Word is that the the 4AF has not much more power than an A15
- 4AGE (double-overheard cam) Impressive power
- 4AGEZ supercharged. Use this motor and its fuel system and computer for a turbo setup. The advantage over the supercharger is that boost can be variably controlled per the wastegate. A supercharger has a fixed design boost.

Much respect to ddgonzal you sound like a wise person!
But where the hell were you before! lol!

Thank you for summerising this long subject!

Cheers Steve!

just a little more info...
difference between a petrol and diesel turbo is its seals, diesel turbos dont have positive seal turbo seals, which means that if u we put it in a suck through system they can leak oil under extreme vacuum, which happens when throttle is closed in a suck through setup, while in blow through extreme vacuum is not build up, so they r ok for blow through, but could give problem in suck through.
barpk