JUST INSTALLED A VOLANT COLD AIR SYSTEM ON A 98 C5, AND DEBAING OVER WHICH H-PIPE, OVER THE AXLE EXHAUST I WANT, BUT I AM CONSIDERING A $600.00 HPTUNEUP INCLUDING DYNO TIME. DOES ANYONE HAVE EXPERIENCE WITH THE HP TUNEUP. THE COMPANY I WILL USE ONLY DOES PERFORMANCE WORK ON GM LS VETTES AND TRUCKS. I AM FROM THE DAYS WHEN WE INSTALLED HEADERS, CHANGED CAMS, INTAKES, CARBS ON STRAIGHT AXLE CARS AND MID YEAR CARS. OWNED 20 CORVETTES AND Z28'S HAPPY HOLLIDAYS TO ALL, LANDSPEED RACER

 

I would save your money until you install headers, cam, etc. No need to pop $600 on a tune for an air filter/catback upgrade.

 

Why you SHOUTING?

 

Would also recommend an X configuration instead of an H.

 

Your MODS really dont justify an EXPINSIVE full tune and YEP,, find a good X pipe!

You already have an H pipe (as poorly as it is designed)

STOCK MIDPIPE:




Dont expect significant gains from those mods!! You might see 15 HP on a good day but 10-12 is the norm.

If your hell bent on a tune, pay the 100-150 bucks for a good mail order tune.

Some other easy bolt on stuff that you can consider to get a few more HP:

2001+ Intake manifold
Ported TB
Under drive pulley

The most bang for the buck are headers.

Example of an X pipe:







BC

 

Welcome to the world of computer controlled muscle cars !!!!
I agree no need for a tune for just a CAI the ECM will learn out for the added airflow on it's own-just give it 50-75 miles of normal driving --These car are pretty finely tuned from the factory--On a bone stocker you may only see between 10-17 RWHP gains with a tune
Better to wait til you've done some more mods
When moving on to other mods a-- dyno tune is not practical on a car that is a D/D and an automatic especially---Dyno tuners run it up to 6000-6500 -check the timing and AFR only there and try to make the most HP there as they can----A "street driven tune" is much better-on an automatic---- they can adjust -firmness-TCC lockup-upshift and more importantly downshift shift points--they can adjust timing for driving in town on the freeway and even WOT--P/T fuel trims as well--- idle or surging issues---
Best of both worlds is a dyno shop that will do both the dyno runs and some street driveability tuning---
The stock "H" pipe is a joke---there is only like a 1" hole betwen the 2 sides-- An "X" pipe is much better as it helps to scavange the exhaust and can get you maybe 3-4 RWHP-- The sound of the X pipe is different---It gives your car a more throaty "race car" note rather than the overdone low flowmaster rumble we've all gotten used to---I love the sound of the x pipe !!!
If you like it loud---run it with NO mufflers --just the cats--Mine is that way--and to me its pefect !! You know about the corvette tax as a previous owner how we get dinged for like $1200 for a set of headers when the basic same set on a camaro is $350 !!!
My exhaust cost me $50 for a magniflow universal x pipe and $75 for welding and adding the axle back 3" pipes $125 total instead of most cat-backs that run from $400-$700
Other "bolt on easy" mods to consider---
1. 160* thermostat ( but wait til you get it tuned so they can re-set the fan settings ) otherwise its worthless
2. LS6 intake----worth about 10 15 honest RWHP ( a 98 still has the ls1 intake)
3. coolant bypass kit--not really able to measure HP but keeps the TB cooler
4. change wires if they are stock w/ TR-55 NGK plugs gapped at .040
5. clean the MAF with brakeclean (oiled air filters often foul the MAF wires)
6 get your T-Body profesionally ported---(Shaner is good) worth about 5-8 RWHP but throttle response is much improved
Good luck and happy C5'ing