Im pushing around 400rwhp with a h/c package on my Ls1 right now with shortie hedders and factory y pipe and which i think might be restricting with my extra airflow........I also dont have a tune yet

with longtubes and a cutout (and professional tune)

what kind of realistic gain to the wheels do you think i should see?

1.with just the upgraded hedders and cutout,
2. with both including the tune..

any advice is greatly appreciate.

 

1. 15 or so
2. Depends on how good the tuner is. My buddy tunes some that add 30 or so. On an H/C could be pretty high increase if you don't have any tune in the car at all yet. Plus drivability will be better and mpg could benefit from a tune as well.

 

i'd wager a good 30rwhp with LT, ORY, and tune.

 

cool..so that sounds like a must have before I go get the tune.thanks.

 

Ditto - I wouldnt be surprised if those shorties, stock Y pipe and cats are holding back close to 25 HP themselves considering the rest of your mods. Once you tack a tune onto that, youre looking at potentially gaining an additional 10 or more.

 

thats exactly what I was wanting to hear.....
Im also going to tune the car with about a 100 shot of nitrous.

 

this might be a dumb question but where exactly should the cutout go?does anyone have any pics......also im wanting to keep my existing borla catback with this setup minus the stock y-pipe,so will that extra length from the cutout move it back at all?

 

I put mine in the I-pipe facing down and out the passenger side just under the rear passenger seat area. The cutout doesn't add length to the pipe it just replaces a section of the I-pipe. Just make sure to check clearances of the ground and being able to get your wingnuts on there when you put the plate on.

 

so what has to be modified for it to fit on the "i" pipe?and how much does that run........also does anyone have a picture of where exactly this is?

 

I'll bet on around the 30Hp mark as well. I gained 7RWHP with LT's and a Tune on a bone stock car. You'll love the tune! A good tuner will give you a good seat-of-the-pants gain! If you take a good look at your "I" pipe under the car, there is a perfect place for it where everyone above described. You'll see it!

 

I sure hope this was a typo!

 

I wish it was... I dynoed at two different places, so I think the first place wasn't correcting their numbers.