Yes, my secondary on my 99s went bad as well. They are a more fragile set of twins albeit mine had over 60,000 miles on them when the secondary started to leak. Initially you couldn't even tell from the visual check under the car.

 

What are the options besides going single turbo? Is it feasible to rebuild them? I'm worried a second hand set of twins might eventually leak again. Ideally I'd upgrade to a single turbo though.

 

Yes, you can rebuild them. They are like any other turbo. Just make sure the abradable seals are fine but I'm sure they will be, and also make sure your exhaust manifold is okay to use again. It is a slightly different shape to the manifolds on the early twins but if you had to you could use a good early manifold with the 99s.

 

Yep, you can rebuild, or by used.

Another option, if you want to stick with the twins is New Old Stock - Ari can get them for you:

RX7.COM | 93-95 Rx7 Turbo