[petmond1]

Hi, I was wondering, I've got a chance to purchase a new set of PSI indy 500 twin pipes. I've got a 91 indy 400, fresh .020 engine, head cut wiseco pistons,clutch kit.I know that I still have to mess w/jetting,clutch, other than that will they work well on that engine? Has anybody else done this? thanks,Pete

 

[ACEXLT]

Not worth the gain considering all the the tuning you'll have to do.

 

[madcow]

i would leave the stock exhaust on that engine, for anything but pure race it wont be much fun.

 

[petmond1]

I appreciate the input, but why do you guys say that it's not worth it, won't be good on the trails anymore please specify. thanks

 

[Polaris XLTSP]

I think that what Madcow is referring to is that if you put pipes on that 500 you move your power band up into the higher rpm's making it much narrower taking away most of your low end torque and negatively affecting the ability to drive smoothly on trails.

 

[madcow]

thats exactly right. plus some engines become supper fussy, you cant jet them fat for safety because they load up when you slow down, then they become to easy to burn down, because you have to run jetting real close. just nature of the beast. it happens on the big twins. with the single pipe they wake up.but add twin pipes and they become sensitive to fuel quality, jetting, clutching, air density.

 

[j-2-800]

You looking at putting 500 pipes on a 400? It will make alot of noise but you probably not be gaining any power. The 500 pipes were designed for 500cc's not 400cc's. Different chamber volumes (tuned pipes)to create horsepower/torque curves. You will probably lose in the end.
Also exactly what Madcow and XLTSP Polaris said.

 

[white lightning]

I have to say I agree with those guys up above. If you want to have a faster and more hp sled, then I suggest you to sell the 400 (they still hold the value pretty good) and buy a bigger sled that suits to your needs. WL.