Building mk indy with a 1997 Honda blackbird engine on carbs . Will this require a CAT as it is on carbs to pass IVA? Regards pete .

for sure it will,

i did a carb blackbird turbo and sva, was not easy to get through emmissions, 3 attempts to do this,

car had to run at 100+ deg to get it through with air pump system into intake system,

i ran a 200 cell cat inside my can and again had to get that really hot also,

good luck and hope you succeed

you will need to work hard even with a cat it will be tough with carbs.

I managed to get my gsxr1100 with carbs through (2nd attempt) and that was under the pre-94 regs which are 10x easier than those post 95.