I do not believe there is a point to having 4 techs to build titans as-is now. It seems like a handicap for people bad at basic arithmetic, and a boring chore for the rest of us.
Why? Having an un-built Titan locks up a large amount of resources for no gain, so there simply is no point starting to build a Titan unless you know you have/will it all funded... at which point you will start the Titan construction and Techs 2 through 4 more or less simultaneously.
There's no realistic opportunity in most games for human opposition to disrupt the process anywhere but at the titan factory (if all those tech centers could be taken down, so could be -or would even have to be- all planets, essentially). So really, the techs don't help with anything.
If these 4 techs really need to exist, perhaps you could make them very expensive and use them to activate Titan abilities instead?
Tech 1: Titan factories and Titans with shields can be built. Very few, weak weapons for sub-capital ship firepower, no movement, no abilities. At this point, it only serves to tank / as latent threat in system, attackers will now have to decide whether it's a good idea to invest something like 6-10 minutes of the fleet firing at it to try and get rid of it.
Tech 2: Movement activated.
Tech 3: Regular firepower activated.
Tech 4: Titan upgrades (Abilities) activated.
And maybe for multiplayer, make it so it can't be seen how much a Titan is capable of until it engages some capital ship or 8 or so frigates.
Even better would be to get the upgrades out of the tech tree and make them buyable per-Titan... but I guess that would require some addition to the game engine - it'd be a shame to dedicate the experience levels to this.