I have k24/18g turbos, inlet pipes, 60lb injectors and a protomotive 91 octane tune, running 91 octane fuel of course. I had a custom exhaust that I picked up from a member here. I ran it while I was breaking in my clutch, but it was miserable loud so I put the stock exhaust back on. I ran at the 1/4 mile here and was able to trap 117 with the stock exaust on the setup. My track is at 2700 feet elevation and is known to be a heart breaker. Any estimates as to what the stock exhaust is costing me as far as trap speed? I was boosting 1.1 bar.

 

Man, I beat that speed with a stock k16 with a tube and straight pipes in Illinois. You should be at least at 125

 

Its costing you the benefit of having the 18g's..

 

Its hard to say I think. When I made a trip to Sun Valley this past week, I was losing tons of power because of the altitude. I do have stock k24s though, with a 92 oct tune.

I doubt it could be robbing you of more than 30hp.. But maybe im wrong? Curious to see what everyone else has to say.

My exhaust drones like crazy, and I contemplate putting the stock one back on every day... haha

 

The elevation is a killer. I think it adds a good half second to ETs and steals quite a bit of MPH. It's better with turbos, but you lose power and spool time starting out and it's probably much less efficient while spooled.

 

Stock exhaust is VERY restrictive. Any mod after a basic flash, will be useless with a stock exchaust.

Think about it, you have almost every mod to get more air in and not letting any out.

I think my car ran 119 BONE STOCK with stock K16's. With your mods and 91oct tune, you should be in the low 120's easy. My guess is that stock exhaust is costing you 6-8mph.

Easy fix. Put your loud exhaust back on and go back..you'll have your answer. It's only an hours worth of work.

 

I believe since you have 18gs that it could be over 30hp and alot more lag for sure..
Love my 100 cell Milltek... Makes power and is on the quiet side,, dyno tested it against a few systems.

 

I trapped 125mph stock with a CRAP 2.2 60-ft.

 

I ran a 11.9@ 127 2.1-60' in the GT2, EVOMS intake, Miltek, unknown flash

 

3-4mph is my experience running at 6-8000 feet of density altitude. Your octane is limiting you just as much as the exhaust.