any mods and exhaust questions

nathann88

[FONT=Times New Roman]i got a little bored of the car, how it was (engine wise) so i looked for some mods 😉 i have fitted a bigger air intake a while back with a K&N Panel filter which helped a little bit. [/FONT]

[FONT=Times New Roman] [/FONT]2 days ago looking for mods i found out about the pre cat that went yesterday 😉 and i blocked of the EGR valve which has helped a lot more much more responsive now.

The exhaust system is standard up to the rear box where it is fitted with an irmscher 2D outlet. 1 of my questions what does the centre box do as mine has seen better days could you get rid of it and run straight through? or would it not work, be to noisy fail an mot? would it make a difference even?

[FONT=Times New Roman] [/FONT]2nd question what other mods can i do to help it run better. i looked at redoing the whole exhaust with a larger manifold but currently a bit pricy for me unless anybody has a link to a good kit?

thanks in advance

Matt

Should be no issue getting rid of the middle box.

nathann88

Hi Matt so would it be road legal? no mid section? would it sound good or as if something has :poop: up?

Matt

No middle sections fine, they sound quite nice as well with the DD back box

stokie

hi a straight through exhaust will past mot i no this as i have a straight through exhaust and my car just flew through its mot

nathann88

No middle sections fine, they sound quite nice as well with the DD back box thanks again Matt 😉

stokie said:
hi a straight through exhaust will past mot i no this as i have a straight through exhaust and my car just flew through its mot

Stokie where did you get yours from ebay? and what do you think of the sound it gives? are you on the same sort of set up as im looking at with the DD backbox?

last question for now any other little mods i can do that improve the performance? thanks for the replys so far 😉 nathan

stokie

i love the sound it makes i aint got the DD backbox ive got a custom box i got it made at my local exhaust shop here a pick. you can do the air box mods veccy intake pipe remove pre cat fit 200 cell cat

stokie

nathann88

thanks for the info i like the look of that box 😉 i think im going to try it with the DD's for now and see what i get. iv already done a bigger air in take and derestricted the air box (altho just looking derestricte post i dont know if i removed top and bottom?) shall be having a look tomorrow lol. pre cat has gone now. im going to look into the 200 cell cat now 😉 more to spend and play about with 😉 thanks for the info and advice again

stokie

you should look at this link he as done some good mods to his car http://www.astraownersclub.com/vb/showthread.php?t=81078

miniator

Removing the mid box makes little difference to the noise of a double D box. Removing the cat does however!

nathann88

miniator said:
Removing the mid box makes little difference to the noise of a double D box. Removing the cat does however!

lol id love to do that but id be the mug to get caught out. this is the trouble now as when you look down this form alone Matt says it sounds quite nice and you say makes little difference.

i dont want it to sound mad just a bit louder as standard is nothing. i want it to have a slight rumble effect. (i like the fact is not loud and you have muppets pulling up along side thinking iv got a 1.4 or somthing and try racing as im 100%debadged 😃)

iv looked at air boxs again and found people drilling out the bottom they say it makes it sound louder? is this true and where abouts do u drill it?
(if it makes it louder and the slightly louder sound with no center box id probs be happy with that)

iv been looking for a 200 cell cat now as well anybody got any links to full systems inc cat and cat back systems? incase i decided to just replace the lot.

Sjdickso

I have a Remus straight through with the DD, IMO it sounded good since then I have put a 200cpi cat and 4-1 manifold in which has increased noise made it a bit raspy.

I thought with the straight through and DD it gave a nice shuttle tone.

miniator

nathann88 said:
lol id love to do that but id be the mug to get caught out. this is the trouble now as when you look down this form alone Matt says it sounds quite nice and you say makes little difference.

i dont want it to sound mad just a bit louder as standard is nothing. i want it to have a slight rumble effect. (i like the fact is not loud and you have muppets pulling up along side thinking iv got a 1.4 or somthing and try racing as im 100%debadged 😃)

iv looked at air boxs again and found people drilling out the bottom they say it makes it sound louder? is this true and where abouts do u drill it?
(if it makes it louder and the slightly louder sound with no center box id probs be happy with that)

iv been looking for a 200 cell cat now as well anybody got any links to full systems inc cat and cat back systems? incase i decided to just replace the lot.

well if you dont want it too loud then removing the mid box is what you want to do.

If your still set on a very expensive 200 cell cat, why dont you cut the cat open and remove the inside of it?? (provided you are keeping the same diameter of exhaust).
will still pass the mot as it is a visual check and is effectively a proper straight through.

Drilling the bottom of the airbox will increase the induction sound. Ive mine done, sounds excellent and although i cant prove it with figures, i feel theres been a performance increase. I didn't drill the box on the engine side though so as not to suffer from heat soak. On a very warm day in traffic you do get a bit of soak still, but once the car is moving theres no issues.

nathann88

Sjdickso said:
I have a Remus straight through with the DD, IMO it sounded good since then I have put a 200cpi cat and 4-1 manifold in which has increased noise made it a bit raspy.

I thought with the straight through and DD it gave a nice shuttle tone.

miniator said:
well if you dont want it too loud then removing the mid box is what you want to do.

If your still set on a very expensive 200 cell cat, why dont you cut the cat open and remove the inside of it?? (provided you are keeping the same diameter of exhaust).
will still pass the mot as it is a visual check and is effectively a proper straight through.

Drilling the bottom of the airbox will increase the induction sound. Ive mine done, sounds excellent and although i cant prove it with figures, i feel theres been a performance increase. I didn't drill the box on the engine side though so as not to suffer from heat soak. On a very warm day in traffic you do get a bit of soak still, but once the car is moving theres no issues.

thanks for the info im going to just order the straight through see if i like it. can always pull it of if i dont 😉
cutting the cat open now thats an idea ill do it in stages, straight through maybe drill some holes in the air box and if i want more empty the cat 😉

how many holes did you drill? i take it you only done it on the wing side as close as you could. any pics?
going back to the cat i thought it got rid of emissions? if i removed the inners the cat would be a pass but would the emissions not fail or am i being thick?

miniator

Yeah i drilled the wing side, 3-4 2" holes with a hole cutter - no pics im afraid.

As long as the engine is running as it should, removing the cat will make no bearing on the emissions readings. Mine sailed through last year without it - emission readings where so low they barely registered!! The law has changed now though saying that if the car had a cat from the factory, it must still be fitted. Ie, its a visual check only.

nathann88

thanks for the info i will do it in stages to get what i want so that i dont over do it. and will be looking at that cat if i want a bit more 😉
im currenty looking on ebay and god knows where else for a straight through would this be fine ebay Item number: 290726444333
Vauxhall Astra Mk4 Hoffmann Exhaust Race Tube (04/98-09/03) - 2 YEAR WARRANTY

i dont see any difference between this 1 and any others apart from some areblack depends on the make. as its just a section of pipe i think this 1 will be fine as it has the extra year warranty what would you say?

si_c1978

im under the impression if you remove the cat internals the second lambda will flash an error at you. as this is the cat operation sensor. i dont believe its a good idea/expensive mastake-a to make-a!
as far as i know no-one except me was running a fully working decat as my aftermarket setup did not require the second sensor. other than that BURT150 has probably gotten closest.......................

si_c1978

i have a 2.25" scorpion setup for sale that would fit a gsi, but not sure on wether it would tie in with the z22se downpipe

nathann88

thanks for the info😉 as for the scorpion setup for sale iwill see how i get on with a straight through 1st