Dear Harikishen95,
If I were you I would save all that money and get myself a bike that's got more scope for modification. As in not just looks.
There is so much so you can do on a Splendour, But it wont make a large enough grin on your face as it would if the bike has got more performance to boot.
Putting a larger tyre on the rear wheel will hamper pick-up, fuel economy and eat the chain and sprockets in addition to the damage your bike's motor is already facing thanks to the ludicrous tail pipe.
In short, save the money and get a better bike. Also keep in mind, Your bike will only loose its value with the mods you've done and have in mind.