I have a completely stock 99 5.2.

I am considering intake and exhaust mods, as I don't want to go too extreme because I primarily tow ky camper with this truck.

Never had a problem besides tranny needing rebuilt, and a missfire on 4, changed plugs and wires and runs great now.

Question is: before I modify, do you guys think that modifying things increase the chance of plenum issue? Like new exhaust and high flow air filter, let's it get more in and out... Faster, harder, hotter.. gonna make chances of plenum issue arise any quicker?

I know I'm not going to see magical performance numbers from filter and exhaust, so is keeping it stock better?

It's got 105k miles. My dad was original owner, I got it at 85k miles. Regular maintenance done. Dash is getting a cap next paycheck. And have changed passenger side axle u joint.

So... Stock or modify? Also concerned that is the exhaust with highflow cat and muffler along with a k&n filter going to do much? Worth it?

 

Modify!!

The plenum IS going to be an issue. It's not a matter of "if", its a matter of "when". Doing mods to the engine (aside from forced induction....) won't make a bit of difference.

The Y-pipe is the biggest restriction in the stock exhaust. So, whatever you do, deal with that as well.

 

Well alright, that was my main concern, I didn't want to hurry along the plenum issue.

I am going to go with the magnaflow high flow cat with y pipe unit. Muffler undecided... And a k&n drop in filter. Think that is all for now, should I expect a lot of gain or is it going to be minimal? Worth the $200 -- help at all for towing?

 

It will probably be noticeably peppier, but, not wrenchingly so. You will like it, and you will get more from any additional mods you do as well. Getting the engine to breathe better is NEVER a bad plan.

 

Great, ill go ahead and do it then. Any advice for muffler? Is the stocker pretty restrictive? I don't want it loud as I take my wife and baby when we tow the camp trailer..

 

I have no info on mufflers. Best bet would be to do a search on youtube. There are a boatload of clips there with various mufflers..... I suspect, damn near anything would be better than stock.

 

Ya, I've been listening to a bunch on there. Just didn't know how the stocker is as far as restrictiveness..

Thanks for all the help!

 

IF you go with the M1 intake, you get rid of the plenum all together.

http://www.hughesengines.com/Index/p...1&partid=11111

 

M1 moves the curve WAY up too high for helping the towing aspect, just my opinion..

hammer, over in the third gen FAQ section, has flow charts on differing mufflers.. it's pretty useful for choosing a muffler for what you're looking for..

my top sub-$300 mods to help a truck for towing out (after modding the plenum) are:

SCT @ $265 (once you address the 'ping in progress' of the plenum, you can safely advance timing to squeeze some go-go.. AND.. you reduce torque management to a huge degree which makes the tuner worth it all by itself.. )

E-Fans for around $150.. (allows you to keep that rascal cool, even during slow speed maneuvering and especially backing with an engine under load.. but the surprise punch?: it frees up that parasitic loss the clutch fan is infamous for.. and gives you likely 20~30lbs of torque punch just above idle- right where you need it for getting a load rolling)

H&S rocker rollers.. around $350ish.. (adds to torque and subsequently HP throughout the range, plus it reduces parasitic loss of power, freeing that up right off the line, again, where you need it most)

exhaust.. $200~$600.. (for the love of God, lose the OE Y.. better flowing cat or lose the cat, get a good flowing muffler.. this may be hard to explain, but I'll try- addressing those critters makes the truck seem like you're losing torque off the line, but you're not.. you're smoothing it out.. whereas before, it seemed to me i would hit the gas and not really jump until i get to about 800~850RPMs, instead now it is smoothly applied from idle on up, and a little stronger methinks... you'll notice it mostly though above 1200RPMs, and it will be evident.)

 

What do I mean by modding the plenum? Just replacing?

Thanks for all the other info man. I only plan to keep this truck for a couple more years. So I think exhaust is where ill start. Soon as its paid for (had to extend loan for tranny rebuild) I'm getting a newer diesel.