I don't have a two-way alarm and cannot comment on the good ones.
As far radar detectors I have a Beltronics Pro RX65 and it has saved me literally thousands in tickets since installing it.
If they're still running the trade-in program you can get an Pro RX65 direct from Bel for a few cents shy of $300 with a 3yr factory warranty that also covers any software upgrades that become available within the warranty period. LOVE IT //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif