Greatest Voyager cover I've ever seen.
And since we know in-story that Voyager was refitted for slipstream, then maybe we could justify this cover by saying that the external modifications were only minor?
I don't think I ever read in any of the Voyager relaunch novels that Voyager's Slipstream upgrades involved heavy hull modifications or new nacelles (certainly nothing as shown in that picture which radically alters Voyager's design).
At best, what I do remember from when the fleet first went back into the DQ to look for remnants of the Borg, it was mentioned that Voyager's deflector harmonics (as well as software) had to have been reconfigured to allow for Slipstream travel - and they used the Version 2 Slipstream which needed Benemyte crystals.
Essentially, even when Voyager was testing that V2 Slipstream in Season 5 episode 'Timeless', the design of the ship itself was unaltered.
The Warp core was what only altered to the point where modifications were ADDED to it, but apart from that, no visual changes on the external ship design were made.
The only thing plaguing the crew at the time was the phase variance (and even still, the ship was able to travel through 10 000 Ly's in 1 minute)... V1 of Slipstream where the maximum speed allowed the ship to travel through 300 ly's in 1 hour (max time that Voyager could stay in) had a problem because the ship was subjected to quantum stresses (hence the invention of V2 in Timeless which needed Benemyte crystals and was faster by 33.333 times) - V2 incidentally did NOT cause quantum stresses on the hull... it just caused the phase variance which forced the ship out of Slipstream in the unaltered timeline when it wasn't properly addressed (of course, the only reason it failed the second time and Kim was forced to disperse it was because the writers wanted to keep the ship still in the DQ).
Sigh... they could have easily made 300 ly 'hops' once per week with V1 alone by making repairs to the hull itself.