A Charger top is on the easy side... the Challenger wide seam is probably the most difficult top to do correctly... not saying it can't be done, but it will be difficult.
It has to be carefully centered and not overstretched when installed. The tricky/difficult part is getting the seam positioned properly relative to the drip rail.... the seam is a gentle sweeping curve that looks pretty ugly if it's pulled crooked.
Another area that can be challenging is below the rear window; if the material isn't stretched just right in the sail panel area and/or positioned just right, you'll end up with a pucker from too much material below the window.


Rick