Hello friends. I have a titan 1 , UK model, totally stock, and have seen in various threads here and in xda about poor reception. Some threads blame the metal rear cover, where the aerials are. I just today received my Mugen 3600 battery with replacement plastic back cover. As I speak now it's on its first charge, so can't comment on it's user time, but I immediately got a boost of 3 bars to my signal on 3g! Where I am sitting now, the max I would get was 2 bars, now I have 5. So this explains why HTC came out so quickly with the Titan 2 instead of offering a replacement back cover for us. Very poor from a great company like HTC I think after you've spent hundreds on a flagship phone! The Titan obviously wasn't tested thoroughly - a bit of tape over the noise cancelling mike to sort poor quality voice issues too. I love my Titan, just a shame HTC don't. WI fi reception is the same, which I have never had any problems with. I would have bought the Mugen battery anyway, as I value long life in a phone- I bought one for my HTC Desire, and had a 1950ma one in my Titan, which was good, and the improved reception is a great bonus. But should you need to replace the cover on your phone to get it to work properly? No, of course you shouldn't.
A quick update on reception - at work the signal was so bad I couldn't send a text most of the time. With the new back cover I now have good 3g reception all the time, and 3.5g at times! No problem sending texts now, and can browse the web, where before a page would never load. And the battery? At 38% after 3 days and 15 hours on its first charge. Not cheap at 55 , but worth it for all the benefits.