I recently purchased my first BMW (2007 335xi MT Sedan). I am looking for suggestions on what performance enhancements to consider (ones that wont void the warranty).

Thanks in advance for the advice!

some company i know offers a piggy back type computer chip for the car the type that you can take off and BMW NA wont know.

gives around 60 hp

search around the forum dude, you'll find lots of info. Lots of options out there from very small to larger tuners, although technically most of them void your warranty if the dealer detects them and decides to blame them.

Rumor has it that BMW will start releasing performance parts for the 335 in the April timeframe. Only genuine BMW parts are covered under the original vehicle warranty.

You're question is vague enough for me to suggest if you can't answer that you probably should leave it stock.

...they back up the warranty you lose with their own warranty that matches BMW's. You won't have to remove anything when you go in for service and you can buy their parts from BMW dealers that are also Dinan dealers.
dinancars.com

Only Parts That Are Proven To Cause The Damage Void That Particular Part Of The Warr. What This Means Is......

If You Put An Intake And Exhaust On Your Car, And There Is An Oil Pump Problem...... Unless They Can Prove That The Parts You Installed Caused The Oil Pump To Fail..... They Have To Cover The Part......

P.s. - I Am Not Entirely Sure, But I Think Bmw Knows When You Put Piggyback Systems On Their Cars......