[JakobM]

I have experience with several EFI units but never used Megasquirt, so no expert in MS, but beleive it should handle a 4 port valve just fine. The port valve is two wire only, same as a 3 port valve. Maybe some of MS users on this board can chime in...

MAC is the producer of 95% of all the 4 port solenoids used.
Below link is 44$ and then you need to pick and buy your brass fittings or pneumatic tube fitting, what ever you prefere - so between 60-75$ total

MAC 4 port solenoid valve
https://www.amazon.com/port-solenoid-boost-valve-46A-AA1-JDBA-1BA/dp/B00A8S16WA/ref=sr_1_1?crid=2JJTM6GYTNZCM&keywords=mac+4+port+boost+solenoid&qid=1563655347&s=gateway&sprefix=mac+4+port%2Caps%2C229&sr=8-1

If you go with normal hose/brass fitting, then you need to purchase

3 x brass hose fitting
https://www.amazon.com/Anderson-Metals-57001-0402-Fitting-Adapter/dp/B004Y74IIA/ref=pd_bxgy_328_img_2/261-5577461-7155657?_encoding=UTF8&pd_rd_i=B004Y74IIA&pd_rd_r=6ea80e93-b5d1-4c75-ad61-57744fdbdc64&pd_rd_w=Tr1OP&pd_rd_wg=Ij1NS&pf_rd_p=a2006322-0bc0-4db9-a08e-d168c18ce6f0&pf_rd_r=CYW6R1MC2QMCGFN5834G&psc=1&refRID=CYW6R1MC2QMCGFN5834G

1 x filter
https://www.amazon.com/Parker-047020002-Sintered-Bronze-Breather/dp/B003Q6CB70/ref=pd_sbs_328_4/261-5577461-7155657?_encoding=UTF8&pd_rd_i=B003Q6CB70&pd_rd_r=6ea80e93-b5d1-4c75-ad61-57744fdbdc64&pd_rd_w=kXsL0&pd_rd_wg=Ij1NS&pf_rd_p=588939de-d3f8-42f1-a3d8-d556eae5797d&pf_rd_r=CYW6R1MC2QMCGFN5834G&psc=1&refRID=CYW6R1MC2QMCGFN5834G