Which One Produce More Gain?

Guys, what do you think should I do? The A'PEXi VAFC II or a good exhaust system for my car. I have a 1997 Honda Prelude Type SH. I did suspension mods and just few bolt ons upgrade. Right now the only thing that's missing from my engine upgrade is an exhaust. Well, I was gonna get the A'PEXi VAFC II and the exhaust but it turns out something came up and I could only be able to afford either one of them. Which one do you think that will give me more power gain? A good exhaust system or the VAFC II? I'm not planning to do anymore engine upgrade after this. This will be the last upgrade that I will do to my engine.

What are your guys input or opinion about this? I've been asking around too about this and some says the A'PEXi VAFC II will give me more gain for the money than an exhaust system but there are also some that says a good exhaust system will give me more gain than the VAFC II because of the OBD II thing.

Thanks for your opinion or input guys.