If it's not really about tuning or wiring. Then it belongs in here.
Has anyone on here used spitronics just looking to know if there any good thinking on fitting it to an r33 rb25det the seem to be very affordable
Not a product I've used before unfortunately. Hopefully someone else on the forums will chime in.
I just took a quick look there and it does indeed look like a very affordable system but one thing you need to consider, who is going to tune it? If it's DIY then crack on but I doubt many shops will be able to help should you get stuck.
Have you looked at the Polish brand of ECU, The ECU Master EMU? They have been making some waves in the UK lately. Price has been their major selling point but they also have the functionality, there's a few shops selling them so there will likely be more support available