Exhaust Help Please

[Tony T]

Hi All

I am new to the forum & require your expert assistance.

Three months ago I had a new fabricated stainless steel exhaust fitted to my 1999 GS300 sport, this included a new cat & full system with twin exit pipes per side.

After the fitting of the exhaust I noticed a drop in power through the rev range, at the time I thought that the car may need to adjust itself to the new exhaust, but it hasnt & the power is still down in comparison to the old exhaust.

I have done some investigation & found that the tubing on the new exhaust is only 50mm diameter compared to the 60mm standard exhaust pipe diameter.

Will this have a negative effect upon the car as it breaths???? & should the company have used this diameter pipe or used a 60mm pipe bore.

All help would be much appreciated, I would like some expert advice so that I can then contact the company that did the fabrication.

Kind regards

Tony

[TigerFish]

No practical experience but I would've expected to get the same guage pipe or bigger. Is that the diameter of the main pipe, or of each of the twin exit pipes?

[Tony T]

No practical experience but I would've expected to get the same guage pipe or bigger. Is that the diameter of the main pipe, or of each of the twin exit pipes?

Hi Tigerfish

50mm is the main pipe size all the way from the cat. The standard was 60mm from the cat.

It's got me baffled as to why they would downsize the pipe diameter. Everybody goes for a bigger size to increase gas flow volume. #%*+€$#%!$$<*€ that's how I feel especially after £600.00 out of pocket.

Just want some professional advice so that I can take them to task, as the exhaust has a 10yr warranty.

[Larkone]

Just did a quick calc and that means the exhaust x-section area with your new system is 30% smaller!! So yes would think that will make a difference.

Numbers are

3.142 x (25 x 25) = 1963.75sqmm

3.142 x (30 x 30) = 2827.8sqmm

[Tony T]

Ihave contacted the company & they have said that they have done 30 GS300 this year with no problems. This though doesn't explain why they use such a small diameter through pipe in comparison to the larger standard system bore. I think this one will take some research to come to conclusion of the idea, that a smaller 50mm bore gives the equivalent or better performance than the standard 60mm. Mmmm search & more research on exhaust performance dynamics.

Thanks to all have helped

Tony

Just did a quick calc and that means the exhaust x-section area with your new system is 30% smaller!! So yes would think that will make a difference.

Numbers are

3.142 x (25 x 25) = 1963.75sqmm

3.142 x (30 x 30) = 2827.8sqmm

[dave1]

Ihave contacted the company & they have said that they have done 30 GS300 this year with no problems. This though doesn't explain why they use such a small diameter through pipe in comparison to the larger standard system bore. I think this one will take some research to come to conclusion of the idea, that a smaller 50mm bore gives the equivalent or better performance than the standard 60mm. Mmmm search & more research on exhaust performance dynamics.

Thanks to all have helped

Tony

It would pay you to look at the advertising which they do to see what they actually say in regard to the spec of their systems. I take it that they are a national company since they reckon to have done 30 GS 300 this year, which seems a lot. Were these 30 cars Series 1, 2, 3 or what? Also, where does the pipe narrow from 60mm to 50mm. as it must surely connect to the manifold or whatever which would be made to connect to a 60mm pipe.