DeathWish said:
I am thinking about adding some mods, and would like to know the ranges for HP gains...
1) Mac Cold Air Intake
2) 10mm throttle body upgrade
3) SLP Loudmouth Exhaust
4) SLP X-PIPE with high-flow cat
thanks.
OK...let me chime in hear...
1. Depends on what you are comparing it to. Compared to stock +5 hp
Compared to K&N, snorkel off, nothing. To all those that say CAI's are worth
nothing--when compared to the stock system with the paper filter they will get you about 5hp. How can the K&N with a removed snorkel yield about 5hp (dyno proven countless times) and a CAI nothing? The CAI's use a K&N or equivalent filter!! Now if you're talking about a kit such as a FIPK then maybe slightly more because of the MAF to TB pipe which is restrictive.
2. I have yet to see a larger TB dyno more horsepower. Funny how every plenum test is the 70mm vs the 75mm. The Modulardepot plenum test shows lower hp and tq readings with the 75mm. I wonder how the 65mm would do. hmmm...
3. Exhaust. Saying this won't yield gains has got to be the biggest myth going. Any aftermarket muffler that is straight through such as magnaflow or borla will yield a minimum 5 rwhp gain. I believe the stock mufflers are chambered which don't flow nearly as well as the straight through. I believe magnaflow has an article where they welded in mufflers (on a cobra) and gained some nice hp. 5.0 magazine did a test comparing mufflers and noise levels. Basically, magnaflow and borla gave the best gains while being the quietest. If you search the net, you will find these articles.
4. The rule is that 1 cat will suck 10hp on a 300hp motor. So on a 260hp motor with 2 cats per side you're talking about 8.5 per side or 4.25 per cat.
So if you go to a 2-cat X-pipe you will add about 8.5hp rwhp. My car dynoed 237rwhp and then 252 with just the addition of pullies and a magnaflow 2-cat x-pipe. Based on what I've seen, I was estimating 6rwhp
from the pullies which would leave about 9 from the x-pipe. Hmmm, kind of adds up.
Say 18-20rwhp.
Hope this helps.
