When I get back from afghanistan I have to put a new motor in my truck. The truck is a 1991 GMC sierra Z-71 and I am putting a new GM 350 in it. My question is what upgrades would you do to help the performance of the Motor? I was thinking a bigger radiator, K&N air filter and a bigger radiator? What do you think and do you have any other suggestions? ANy help would be appreciated. Thank you

K&N filters are so overrated, stay stock.
Got a transmission cooler?
It may not hurt to just spend your dollars on a lot of preventative maintenance. Transmission flush, differential fluid change, brakes, hoses, get it detailed and looking good, etc.

What about a HD water pump

Ditch the 350 for a built 383..

Ditch the 383 for a big block. If your gonna run you may as well run.

matt

But then my gas mileage would be even lower

trans cooler, keep the same radiator, make sure your cats are in specs on backpressure, flowmaster muffler system, k&N filter(when used properly, they work)..... stock size tires (oversized tires are a gas mileage killer).

Stock size tires are what I have on it. What about putting new headers on it? Any suggestion ON type? The cat is original, Should I put new one on? I thought about turning it into a true dual, is it worth it?

Any recommendations on a trans-cooler?

not really worth the trouble of headers and true duals. just open up the exhaust a little bit with the flowmaster. a little will help, a LOT(headers, true duals) willbe a headache. (mroe maintenance and another cat to buy)

Should I replace the CAT? Any suggestions on Trans Cooler?

If i'm not mistaken his truck already has two cats. I know my 97hoe did, then a y-pipe into a single muffler. Headers will be good imo for sound atleast. Get longtubes not shortys whatever u do.

I am not concerned with sound. I think it only has one cat but I will check. I had it turned into a dual exhaust after the the muffler. Would header help gas mileage and performance?

any suggestions on brand of Transcooler and is one with a fan on it necessary

ttt

Again i'm not sure about your truck but my tahoe came with a trans cooler from the factory so maybe it already has one? You have the older gen. 350 so some things could be different from my vortec?

I used a Hayden transmission cooler on my 4runner. Never had a problem with it leaking and it seems to do a great job. You shouldn't need a fan for the cooler. It just sits in front of your radiator.

If you are worried about cooling and fuel economy you might want to look into an electric fan. If yours still uses a fan clutch then an electric fan can usually pull more air and put less drag on the engine.

How hard is it to put a new fan in? and by fan do you mean the fan attached to the radiator

Yes the cooling fan behind the radiator. On most (especially older) rear wheel or 4 wheel drive vehicles the cooling fan runs off an accesory belt with a fan clutch.

So how hard is it to change out the fan

http://www.youtube.com/watch?v=ZZVr2HlCMWM

this is a must have