I needed both 45 and 90 degree for mine. The 45 degree ones for the exhaust side, you route the pliers through the bulkhead to reach the cap. The intake side you can do from the top with the 90 degree ones.
I am sure you can do the exhaust side with the 90 degree as well, I just couldn't get the right access and found the 45 degree jobbies made it easier. As I had both (in the same packet) it was straightforward.
I pad about £10 for the pair from Sealey.