Just FYI On ebay you can get just the mufflers for about $150 shipped (sometimes less). if you are looking to save some money. I bet the have sounds clips.

 

There's only one way to insure you're getting the sound you want, that's with an aftermarket exhaust. Word of advice stay away from the junk they sell on ebay, buy from our sponsors here on Driver then you'll know exactly what you're getting! You might try our MARKETPLACE for one of our members demoding his car for a HKS or F1 exhaust, that'll save you 50% of the cost....
Gary

 

Is there any way in which I can keep the original sound of the exhaust but gain some power?

 

nice two yr old bump. the only thing i can think of would be to get a plenum spacer and mrev2 (mrev2 for 6mt). that should add some ponies without changing the sound of the exhaust. like its already been stated adding in hfc would amplify the sound of the exhaust without changing that g35 exhaust signature. not sure if ur question refers to keeping the exhaust exactly the same as stock or just keeping the g35 exhaust sound.

 

The Nismo exhaust offers the stock sound that's a bit louder. Not exactly stock (its stock-ish..?), but its a nice upgrade and you may as well spend the extra money to get a legit exhaust that you can add to your extensive list of upgrades.