CNC transition head flanges that are really nice to use. I have a set. https://turbo-flanges.com/index.php/...ad-flange.html
Their prices have gone up a little but $5.35 a piece for sch10 1.5" long radius bends aren't too bad. https://www.aceraceparts.com/collect...ls/schedule-10
. You'll need some short radius 90s as well in case you have some tight spots but realistically if you plan it out enough you can get away with just long radius elbows. UPP has short radius weld els under $5 a piece and some really nice sanitary 2.5" and 3" pipe but shipping to Canada would probably kill you.
If you want to get serious about building stuff or just make it a lot easier, then check out PRL Motorsports fabrication tools https://prlmotorsports.com/fabricationtools.aspx
. I have their 1.5" sch pipe jig and it makes it very simple to cut angles out of those bends with a bandsaw. Their purge block for turbo flanges is really nice too. LPSFAB's CCF V3 cutting fixture is really nice as well for building collectors but again all of those things are quite expensive and not necessary for a 1-off. https://www.verociousmotorsports.com...utting-Fixture
You could build everything with a grinder and chop saw if you want.