you don't need drive tech - just lots of size 1 missiles - my combat group has 14 6kT corvettes with 3 MFCs adn 6 launchers and 300+ missiles....
I then have a similar force of corvettes with size 9 launchers with a long range missile that dows 5 damage - older ones have a 65mk range - my new ones have a 85mk range
I have several Awacs ships with this force - spread around - each has an active R100 sensor with 350mk range so I can see the bastards coming and a R1 with only 20+mk range - the key stat is the size 6 missile or smaller range which is 4.8mk - this is the effective range of my AMM - once incoming missiles are detected I direct half my AMM frigates to open fire (assuming a large incoming group of missiles) with each MFC on each boat targeting a different missile salvo where possible ot improve spread - I have found that 6 missiles from 1 launcher at a salvo might kill 1-2 where as 2 launchers each from different ships will do the same or better...
so then 5 secs later the other half of my AMM frigates open fire - i have 10 second re-load so they can pump out 41 missiles per 5 second round - haven't found any Precursors yet than can get missiles through - helps if you turn away too if there are lots of incoming - lengthens their flight time and allows you more AMM rounds.
14 ships firing 4 Warhead 5 missiles each generally kill even the biggest Precursor ships in two salvos - but I also have a warhead 12 size 9 missile with 14mk range I use to finish any tough nuts off...

That's pretty much what I'm doing now as a pre TN start will leave you badly in need of resources, so hyper expand and make individual less important making individual unit worth next to nothing.

I was more thinking on actual NPR aggression. But probably one could always build a swarm of icmb drones, making the technology gap less relevant.

I would go for Ion engines and missile tech around the 8000 rp mark.  Make sure your missiles have a good chance to hit a target moving at 5000km/s and bring along a lot of point defense, you will need it if you run into a larger precursor fleet.  Other npr races should have tech somewhere around the same as yours so it shouldn't be to bad.  The down side to this is that missile combat uses a LOT of missiles and you are going to need a lot of ordinance factories to keep up with use.  If you don't then you may have a problem with the NPR running you out of ammo and sailing in to destroy you because of this.

Brian

The effort it takes to take out precursors and exploit ruins seems to be about as much, if not more, as just doing the research yourself, at least from what I've seen so far... but maybe if you get lucky with higher tech ruins it's worth the trouble?

I know there are at least a couple of tech types you can only get from ruins - are they really worth it?  And how likely are you to get them?  Seems pretty low to me, but I've only exploited a couple of ruins so far, so maybe I've just been unlucky.

It depends on how you start and how many and what kind of ships you have to fight.  Some times you get lucky and although they are higher tech it is not all that hard to clear them out other times you are not so lucky.

If you turtle you miss out on early ruins and possibly NPRs to conquer both of which can be a great boost but come with danger.

The effort it takes to take out precursors and exploit ruins seems to be about as much, if not more, as just doing the research yourself, at least from what I've seen so far... but maybe if you get lucky with higher tech ruins it's worth the trouble?

I know there are at least a couple of tech types you can only get from ruins - are they really worth it?  And how likely are you to get them?  Seems pretty low to me, but I've only exploited a couple of ruins so far, so maybe I've just been unlucky.

I'm currently playing a game with 10 starting NPRs and an NPR-generation chance of 0, just to see what it's like.  I'm about 25 years in now, and while it's not actually that slow to update there are one or two battles a year that take a few hours real-time to resolve using Auto Turns. Luckily I have several computers and typically just throw on a movie when that happens.

I've explored about 30 systems and I have not actually encountered anything but the Swarm and several bunches of what appear to be Precursor wrecks yet.  I'm actually wondering whether most of the battles I'm seeing are Invaders vs NPR and by the time I actually do find their homeworlds there will be nothing left but smoking, twisted glass. Or maybe they've run out of minerals and are dead in space, who knows.

The downside of turtling is money, you can afford more ships with more population and more trade. Although without a very active colonization effort it takes a long time before the colonies make themselves felt.

But sometimes it doesn't matter. I started a game with 1 NPR and I'm pretty sure that this NPR is one jump from Sol but around 2 secondary stars which orbit the primary at over 1600 billion km, and there are no LPs. So they will never reach a jump point themselves.