Boost controller question

[DannyG]

So my buddy has a WRX with a full 3" catless turbo back, and he's having problems controlling the boost. It spikes all over the place, and there are no boost leaks whatsoever. He was told by Shiv from Vishnu that if he doesn't have a hi-flow cat, he will run into that problem. I call BS... but then again I don't know very much about these cars. Does anyone have any insight on this issue?

Thanks

[Cosmo]

I haven't had that problem, and I've been catless for 9 months.