Q. I have Royal Enfield Classic 350 cc gunmetal grey 2019 abs model. I want to change its stock silencer into dolphin silencer. Will it effect my bike engine or mileage of my bike - Bullet 350?

All the extra you input in your bike will eventually affect the performance in some manner, sooner or later, May be you won't feel any changes in short run, but it may Occur in long run of the bike, and these specifications are not only limited to Royal Enfield, its applicable on all the Bike manufactures, so check the compatibility of any extra or after market inputs.

Yes definitely it will affect your bike in terms of mileage and speed and can affect the engine after long term use. You might not feel the changes in your bike in early days but after some months you will feel that it was not a good decision. Keep your bike as it is, you can add cosmetic changes in your bike like wind shield, stickers, backrest, hazard indicators.

RE now sells RTO approved / legal on-road , various types of silencers. Check your nearest RE showroom or website for latest updates. If you buy it, then it shouldn't be a problem in warranty/mileage.