Bear in mind most people use the smaller td04s on their 306s, mostly because the larger td04s are just too big to spool without help and still be drivable. The td05s are another step larger, definitely too big to use on it's own imo. To give you an idea, i have one of the smallest td05s going and it should (according to my calculations, don't rely on that lol) be about the right size to compound with a standard 306 turbo, this is it:
As you can see, the hotside is pretty large in comparison to a standard turbo and they only get bigger - ie later spooling and more laggy.
If you're sticking to a single turbo you'd be best off with one of the newer garretts or borgwarners, td04s are only so popular because they're cheap and indestructable. Compared to the gt/K range they're pretty old-tech and inefficient, depends what you want from the install really.
Edit: i am fairly large, use the key as comparison for size lol.
As you can see, the hotside is pretty large in comparison to a standard turbo and they only get bigger - ie later spooling and more laggy.
If you're sticking to a single turbo you'd be best off with one of the newer garretts or borgwarners, td04s are only so popular because they're cheap and indestructable. Compared to the gt/K range they're pretty old-tech and inefficient, depends what you want from the install really.
Edit: i am fairly large, use the key as comparison for size lol.