I have an HT3B that I bought off this guy and it came with a 32cm housing and a 23cm housing. Would the 23cm housing be good as a single turbo or would it be too laggy and not good spooling at all?

 

I wouldn't run it as a single. That's a big turbo to be driving on the street. If it were a pull truck only I'd try it. It would be a good bottom turbo in a set of twins.

 

What tweaks you running in the P7100 pump? I would run at least 5k gsk or more, so you get abit of useable rpm on the turbo.

I think that turbo would work better as a primary turbo in a set of twins under your 64mm. I would find a different turbo that has a smaller turbine housing. That turbo is going to be a laggy beast and smokey.