Welcome Mike 1..I agree Dave those three make , Are we going to start the swaybar debate ? If you aren't taking the trucklet to the track don't worry about the bar....see the track results from Nürburgring. If you are buy the Powell...............

 

My car is a manual, and thanks for the tips.

 

Just a FYI , about tunes, in general.
A good E47 Ethanol tune, is the best tune, for our buggys,
if you have Ethanol in your area.
Excellent street, & strip, manners, & gobs of wonderful torque...
And I always thought, that the Ethanol, is what made for the excellent, every day, nice & crisp, throttle response.
BOY WAS I WRONG !!!
It's that K&N intake tube...
Since it's near the end of winter here, & racing season doesn't start,
for another month, I've been messing around, with things...

I reload my GMPP tune, into my buggy, for the 1st time, in years.
With the K&N air system, & the Turbo-Tech engine mount, still in place, this factory tune, is a BLAST, for every day, stop & go normal, daily driving.
There's a guy, in another thread, on this forum, post #18, that listed the tube/fitting,
part number, that you can buy, from K&N, shipped to you, for under $50.
If you don't want to spend the money, for the complete kit, this is your
best way to go...
Post #18 in the following thread:
https://www.chevyhhr.net/forums/2-0l...ference-53046/
Add this $50 tube mod, to the do-it-yourself, coring the 2nd cat mod, & you will have removed both the intake restriction, & the
exhaust restriction, that our buggys have. Plus the tube will give you great daily driving street manners, with the nice crisp throttle
response. And as an added bonus, the tube, will move your LTFTs closer to zero, as both the stock factory tune, & the GMPP tune, have up to +8 , LTFT values.
Almost forgot about that horsepower thing...… by removing both the intake & exhaust restrictions, you WILL gain, at least 15HP...
Also, as a WARNING...…never remove the 1st cat, as it is a very important component. It doesn't restrict power, & it helps maintain, an important, air-charge balance, that is locked, into the ECM, in tables, that nobody can change. I ran 12.3s, all day long, my last time at the track, with the stock 1st cat, in place, leave it alone...
Damm, I'm sounding like an informercial now...

 

What happens when you go full catless?

 

Shane H, that would be my question as well. I have a 3" SS exhaust I'm going to be installing on mine. The down pipe is cat less, although I have a GM Performance cat I can install.

 

You lose out on nice, crisp, everyday driving, throttle response. It will feel like losing some,
low speed torque. Plus with all my testing over the years, I really didn't see
any gains at the track, going catless.
If it would help my buggy, I'd go catless, in a heartbeat...
My last two runs down the track, were back-to-back, 12.33s, with the stock 1st cat, in place...
https://www.chevyhhr.net/forums/hhr-...t-power-43170/

 

Thanks for the link, very interesting, you certainly are doing a bunch to testing. What are you using for a torque converter? With these cars I would think the auto is going to beat the stick every time if you get the converter sized right. The auto is going to shift the same which is going to keep the turbo loaded up better even with the NLS being used on the stick car.

 

Stock convertor works just fine..
Brake-Boosting, at the line, is so sweet…
Here's a 1/4 mile run, highlighting, with that vertical straight white line, 5.9lbs of boost, at the line, at 2,629 RPM
If you follow the top red, RPM line, of the graph, you will see the 2 shifts, into 2nd, then 3rd.
If you follow the top green MPH line, you will see, a smooth increase, with no wheelspin.
The most important line on this graph, is the straight, wideband , (WB B1), baby blue in color...
You can also see, at the bottom, 100% throttle, by me, & the ECM, sometimes, if the ECM, doesn't like what it sees,
or the slicks break loose, the ECM, WILL, throttle back, even with your foot, petal-to-the-metal...
This chart , I believe, is a 12.4s ET , pass, down the track.
So yes I have, the stock 1,600 RPM torque convertor, sitting still, at 2,629 RPM, as the result of 5.9lbs, of boost, pushing against it...
At this point, the brakes are barely, holding, the car in place, & sometimes, if I don't have the brakes pumped up hard, my buggy will start to creep forward, causing a red-light start...
Sort of like a jet, on a carrier, going into afterburner, before launching, off the deck...

 

Need a trans brake. I can't read the graph clearly, is it sliding into gear on the up shift? I HPTuners also.

FWIW the hold back bolts on a Navy fighter launched off the flight deck will hold the plane at AB. It's the jerk of the cat that brakes the bolt during launch. Heard of a cold cat shot? that's when the cat breaks the bolt but doesn't have the force available to launch the plane, at which point the plane falls of the flight deck into the drink... bad day.

I was flying Navy from 72 - 76. sad time for military people.

 

Don't know if they can do a trans brake, for the 4T45E…
Chart is crystal clear, on my computer screen…

60' times 1.6s , & 60 MPH times under 4 seconds, with boosted launch...

Thanks for your service...