Here are just two examples.

On one, I cut the pipes at the cowl. The cowl was straight and that's where the cuts had to be. The original length of the pipes was gained back with the extensions. I didn't choose the length however to match that length.

On the other, I left the pipes the original length because the angled cowl would reach around them.

On two-cycle engines, very often you can change the length of the exhaust pipes without any measurable effect on the engine. It depends on the design of the muffler and how the exhaust pipes play in that design. Lengthening does increase backpressures but we can almost always get away with short or moderate increases.

There is a silicon tubing sold in hobby shops that works better than the lighter, special purpose exhaust routers. It's the blue stuff in one of the pictures.