Just picked up a Redline 925 which I really like. The ride is good and it's fit me well, which wasn't the case with my last two bikes (a conversion and a Pista). Only issue is that it's pretty heavy. I assume most of it is in the frame, so there's not much to do about that but was wondering how heavy parts like the stock Alex Rims are compared to something lighter from Mavic or Velocity. Would replacing the wheels make a big difference? What about swapping the fork for something carbon? Not talking weight weannie ounces but real pound or two type of stuff.
The bike has Alex G2000 rims. Those weigh 590g. A Velocity Aerohead weighs 425g, a Mavic Open Pro 435g. Replacing the wheels would cost $250ish for decent handbuilt wheels, and probably feel nice. However, it would make a weight difference of a bit under a pound. That's not terribly worthwhile to me.
If you don't mind chainring tattoos, you might buy different chainring bolts and take off the chain guards. If you don't mind getting your bike messy, making your rainy rides suck, and getting whatever fluids are on the road sprayed on you, take off the fenders. Maybe replace the handlebars & stem, especially if you can find something nice used and especially if you'd like to tweak the fit.
But overall, I'd say the Redline 925 is designed more for utility, durability, and cost than weight. Making it a light bike would be difficult and probably mean losing some of its advantages in the utility, durability, or cost categories.
I had a 925 and when I got it there were no fenders or misc parts. I found it to be a nice ride and maybe not real quick handling but I still liked it. I think it weighed 19 pounds. The stock parts were just fine for me at that time.
I agree with AlanKHG on his points. If you are really into saving weight than maybe look into a lighter frame for starts.
I've had lighter bikes but I do like the ride of this one and with all the rain we've been getting here in NY I appreciate the full fenders and not having to tuck in my pants leg or worry about laces with the chain guard so screw it.
I've replaced all parts where I interface with the bike (bars, grips, seat, straps, clips and pedals) and it's dialed in.
The only way you could significantly impact the weight would be by replacing nearly all of the parts, which is going to cost $$, especially for light stuff. A pound or two is barely going to impact how the bike performs . It would probably be more cost effective to replace the frame. If you want something light, save for new bike.