Right. What a muppet. Looked up codes and it was pointing towards a leaking air intake so today I took a good look at the T pipe mod. It turns out it was fine but I tweaked it anyway. The problem was when I did that I replaced the O rings in the intercooler pipe. The big U shaped clip that holds it tight to the resonator hadn’t engaged so it had popped off slightly. Fitted everything back together and double checked. Took out for a spin and all is well