Parts with small influence on PI

Just generally interested in what parts u guys playing around with when it comes to not to exceed a certain level?

Rim size
Bodykit parts (rear bumper, sideskirts, hood)
Oil and Cooling

usually I try to go as light as possible, but in some cases I have to add weight to get some other part in, Like use very heavy rims just to get race weight in, or something like that.
Sometimes Intercooler has more effect on weight than power, and reduces PI, but in this case it’s almost always better to check can you remove some other part for 1 or 2 PI

How ever before yuo really start setting the final build test drive the car when you are 2-10 PI off If it drives like cr*p you get good idea what the car needs most at this point.

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didnt ever notice rim sizing would make any difference my bad lol great advice, thank you!

I always leave for last the rim sizes and driveline. And, sometimes play around with adding add’l size on rim versus DL, you can actually save several lbs. You can also go higher weight on rims then swap rim size and DL around for weight reductions.


drive line, brakes, roll cage, rim, rim size hood/bumper and sometimes flywheel and clutch,

If I don’t have enough PI to add more power I get lighter rims, then add driveline if possible.

Brakes - sport brakes sometimes drop PI due to weight without hurting performance.
Roll bars - specifically race for tuning
Suspension - run street or sport if doing power build and overall it handles ok without race
Roll cage - if drops PI or only adds a few PI plus lowered 0-100 times. Watch out for excessive weight gains.
Oil and cooling and/or intercooler - watch the weight added. If it’s minimal it’s good way to drop PI
Differential - no PI effect for race and it’s tunable
Transmission - street or sport if PI drops only
Rims - heavy rims lower PI and sometimes the added weight is needed or it doesn’t effect performance
Rim size - very very very important. Run 19-21s and car will handle better, have better top end, and drop PI. Common trick is to use lightest rims and 18s-20s to get lower PI, lower weight, and better handling.
Rear Tire width- almost no or negative PI effect for FWD, reduces PI for awd, and minimal costs sometimes for rwd.
Forza aero - helps with handling and minimal pi effect
Other body parts - only if they lower weight.
Any of the 3 power upgrades after camshaft. Usually street provides better performance than street intake.

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so many great responses thank all of you guys! special thanks to you Swerve, you saved me a lot of time :slight_smile:

and if you set the car list in class order, the order is in pi and so the ones at the top a less likely to gain pi and still stay in the class (and the ones at the bottom is easy to improve them and stay in the class).

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i’ll try this next time. usually picking cars sorted by year (2010’s and 2000’s) but i can be converted :slight_smile: