SCguy58

I have a sc300 and I am planning on buying two HKS universal hi-power mufflers, but can't decide which inlet size to go with. The two options are 75mm and 60mm. If I were to go with the same size piping into the cans, would I be loosing power if I went with the 75mm? I would think it wouldn't be a big deal because the piping would be the same size until it reached the cans. I just think the smaller can looks way too small for our cars and would like to get a bigger one, but if I have to sacrifice a big loss in power then I may just go with the smaller one.

mkorsu

By just putting on an aftermarket muffler alone you're barely going to see any power increase anyway so I don't think it matters what size.

SCguy58

So even if I did change the size of my piping to 2.25, I wouldn't see a difference between the two cans because the inlet sizes are above 2.25?

vipsoarer

if you change the piping it will add some power but dont expect a ton. the truth is you want to match your piping size to the exhaust flow. the dual 75mm would be overkill but if you like the look and understand that you wont be making any power gains from going to the larger pipes then go for it. people claim you lose power from lack of backpressure but the reality of it is, its barely noticeable if at all for cars with only bolt-ons

SCguy58

Does any one have pictures of the HKS hi-power mufflers, both the small and the large can on our cars?

kaotiq

I have dual hi-powers right now with the 75mm inlet. Lemme tell you something. THese mufflers are HUGE and kinda loud. It really catches a cop's attn. Unless you're running FI, i do not recommend getting the 75mm

SCguy58

kaotiq, what size piping do you have and do you have your resonators/cats removed?

kaotiq

From my T78, I believe that it's a 3" (or possibly even 3.5") downpipe to a 3" midpipe to a 3" inlet/outlet sport cat and 3" piping all the way thru the mufflers. I hope that helps.

SCguy58

would the 75mm cans be loud even if I left the stock piping and resonators, until I turbo it?

rscott

FYI with all exhaust piping/cats the same, an NA car is usually louder than a turbo car. the turbo itself muffles the sound alot. if kaotiq is saying that 75mm is loud with his t78, its going to be loud on your car. Granted, the sound level does depend alot on the manifold design also, 75mm piping is going to be loud either way. Also, match the piping to your mufflers. if youre planning on a large turbo, get the piping to match the application. for moderate boost levels a 3" dp to ~2.5" after the split should be fine.

SCguy58

Does anyone have pics of dual 60mm cans on their car?

SCguy58

If I went with the 60mm inlet mufflers, then I should get 60mm piping? In the future when I turbo my car, would the 60mm piping be a little too small? When I turbo my car I am planning on going with 2.5in. piping because I am going to keep the dual exhaust. In your guys opinion which would be the better size inlet to go with in the long run, 60mm or 75mm?