2000 GMC SIERRA SLE C3500 7.4L DUALLY MODS ???

Hi, last year I bought (only 5 500 CAD$) this 2000 GMC SIERRA SLE C3500 7.4L DUALLY.

It is really clean, 72,000 miles or 114,000 KM not rust. I added the decals because at some point the paint started to peel.

Right on purchase every mechanics that looked under it tried to convince me to don't buy it... They wanted it for them   So after an oil change (non-synthetic for engine and synthetic for the transmission) I adapt my driving to this wide truck.

It is equipped at the rear air bag "air lift" with control within. I changed the air filter with a K & N E-1796. The "Ground Effect" kit add some looking. Some like, some dislike. Anyway after 12 years on the truck I won't remove it. Less trouble....

I use this truck to tow my fifth wheel, then I would like to keep his work horse vocation.

So after hours of looking on the web and after finding tail lights, head lights, spark plugs, cold air intake and many but no so useful parts for the moment.

I wrote to you guys of Truckin' to know where to start cranking this truck. I would like suggestion from low budget mods to high budget mods.

First I'm looking for the best cold air intake. Performance and sound please.

I didn't find any programmer that increase my HP or Torque.

I thank you all in advance.

I'm not use to forum posting but found this place very time consumming in a good way!