I did this swap in my 09 R/T and was very disappointed. You do get about a 1/2" drop but the ride is poor at best. After about 300 miles I swapped everything out for the Eibach setup and it was the best thing I could have done. Much better ride and handled better too.
Its been awhile since I made this switch to my R/T but I thought it was very worthwhile. I think it was about an 1" drop and the handling was much improved. I didnt think the ride suffered either. I have a 2010 maybe that makes a difference.
My car came with the SRT8 suspension installed from previous owner. I understand the drop to be 1" to 3/4". My car is a daily driver and I am 32 so not that into sacrificing ride quality for cool looks. I thought the ride has been really great for a two door muscle car. Really for any car. My wife, our two kids, and myself load up in the Challenger for road trips. We leave the Tahoe at home.
Make sure you don't have the Nivomat self leveler shocks/struts or you won't see a with any springs.
I wonder if there is a suspension resource that shows what your drop is from each product. I have the SRT springs and shocks on my 09 R/T. I've heard 3/4 to 1" drop from that. I see other cars with Eibach or MOPAR stage 1 springs and they say about the same drop or more.
The MOPAR Stage 1 springs may be what I am looking for then. I'll have to search a SRT8 vs 09 R/T Track Pak swap and see what those numbers are. I just don't want to buy Eibach or MOPAR springs to have similar or little drop.