Okay so I have a 03 Tl and I want to build an engine that's got more power but is still capable of being a daily driver. I'm not very familiar with these engines but Ive read a little about building a 3.5 or even a 3.7 Any input on what I should do will be helpful.

 

I'd suggest you do a 6MT swap before doing and engine work. With an already glass AT, any power gains you do will only kill the transmission faster

 

^^ This

Do not significantly mod your vehicle unless you've solved your transmission problems.

An AV6 is an alternative route if you don't want to do the MT swap.

 

Pick up a J35A3 out of an MDX, bolt on some headers, CAI, and lightweight pulley, can be done for less than a grand if you do the labor. I did this plus head work and J32A2 cams on a trans with over 200k miles and still got another 75k out of it (the last 10k were supercharged). When the trans goes AV6 or 6-speed swap. Change the fluid regular, keep the A-B solenoids in adjustment and replace pressure switches every 30K and keep on rocking!